diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-07-26 17:39:54 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-07-26 17:39:54 (GMT) |
commit | f01ef569cddb1a8627b1c6b3a134998ad1cf4b22 (patch) | |
tree | 29ea1a0942c8549c24411e976cd6891c7e995e89 | |
parent | a93a1329271038f0e8337061d3b41b3b212a851e (diff) | |
parent | bcff25fc8aa47a13faff8b4b992589813f7b450a (diff) | |
download | linux-fsl-qoriq-f01ef569cddb1a8627b1c6b3a134998ad1cf4b22.tar.xz |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback: (27 commits)
mm: properly reflect task dirty limits in dirty_exceeded logic
writeback: don't busy retry writeback on new/freeing inodes
writeback: scale IO chunk size up to half device bandwidth
writeback: trace global_dirty_state
writeback: introduce max-pause and pass-good dirty limits
writeback: introduce smoothed global dirty limit
writeback: consolidate variable names in balance_dirty_pages()
writeback: show bdi write bandwidth in debugfs
writeback: bdi write bandwidth estimation
writeback: account per-bdi accumulated written pages
writeback: make writeback_control.nr_to_write straight
writeback: skip tmpfs early in balance_dirty_pages_ratelimited_nr()
writeback: trace event writeback_queue_io
writeback: trace event writeback_single_inode
writeback: remove .nonblocking and .encountered_congestion
writeback: remove writeback_control.more_io
writeback: skip balance_dirty_pages() for in-memory fs
writeback: add bdi_dirty_limit() kernel-doc
writeback: avoid extra sync work at enqueue time
writeback: elevate queue_io() into wb_writeback()
...
Fix up trivial conflicts in fs/fs-writeback.c and mm/filemap.c
-rw-r--r-- | fs/block_dev.c | 16 | ||||
-rw-r--r-- | fs/btrfs/extent_io.c | 2 | ||||
-rw-r--r-- | fs/ext4/inode.c | 4 | ||||
-rw-r--r-- | fs/fs-writeback.c | 373 | ||||
-rw-r--r-- | fs/inode.c | 5 | ||||
-rw-r--r-- | fs/nfs/write.c | 3 | ||||
-rw-r--r-- | include/linux/backing-dev.h | 8 | ||||
-rw-r--r-- | include/linux/writeback.h | 55 | ||||
-rw-r--r-- | include/trace/events/btrfs.h | 6 | ||||
-rw-r--r-- | include/trace/events/ext4.h | 6 | ||||
-rw-r--r-- | include/trace/events/writeback.h | 183 | ||||
-rw-r--r-- | mm/backing-dev.c | 82 | ||||
-rw-r--r-- | mm/filemap.c | 6 | ||||
-rw-r--r-- | mm/page-writeback.c | 280 | ||||
-rw-r--r-- | mm/rmap.c | 4 |
15 files changed, 747 insertions, 286 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index c62fb84..f55aad4 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -44,24 +44,28 @@ inline struct block_device *I_BDEV(struct inode *inode) { return &BDEV_I(inode)->bdev; } - EXPORT_SYMBOL(I_BDEV); /* - * move the inode from it's current bdi to the a new bdi. if the inode is dirty - * we need to move it onto the dirty list of @dst so that the inode is always - * on the right list. + * Move the inode from its current bdi to a new bdi. If the inode is dirty we + * need to move it onto the dirty list of @dst so that the inode is always on + * the right list. */ static void bdev_inode_switch_bdi(struct inode *inode, struct backing_dev_info *dst) { - spin_lock(&inode_wb_list_lock); + struct backing_dev_info *old = inode->i_data.backing_dev_info; + + if (unlikely(dst == old)) /* deadlock avoidance */ + return; + bdi_lock_two(&old->wb, &dst->wb); spin_lock(&inode->i_lock); inode->i_data.backing_dev_info = dst; if (inode->i_state & I_DIRTY) list_move(&inode->i_wb_list, &dst->wb.b_dirty); spin_unlock(&inode->i_lock); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&old->wb.list_lock); + spin_unlock(&dst->wb.list_lock); } static sector_t max_block(struct block_device *bdev) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 7055d11..561262d 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2551,7 +2551,6 @@ int extent_write_full_page(struct extent_io_tree *tree, struct page *page, }; struct writeback_control wbc_writepages = { .sync_mode = wbc->sync_mode, - .older_than_this = NULL, .nr_to_write = 64, .range_start = page_offset(page) + PAGE_CACHE_SIZE, .range_end = (loff_t)-1, @@ -2584,7 +2583,6 @@ int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode, }; struct writeback_control wbc_writepages = { .sync_mode = mode, - .older_than_this = NULL, .nr_to_write = nr_pages * 2, .range_start = start, .range_end = end + 1, diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 678cde8..3e5191f 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2741,7 +2741,7 @@ static int write_cache_pages_da(struct address_space *mapping, index = wbc->range_start >> PAGE_CACHE_SHIFT; end = wbc->range_end >> PAGE_CACHE_SHIFT; - if (wbc->sync_mode == WB_SYNC_ALL) + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) tag = PAGECACHE_TAG_TOWRITE; else tag = PAGECACHE_TAG_DIRTY; @@ -2973,7 +2973,7 @@ static int ext4_da_writepages(struct address_space *mapping, } retry: - if (wbc->sync_mode == WB_SYNC_ALL) + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) tag_pages_for_writeback(mapping, index, end); while (!ret && wbc->nr_to_write > 0) { diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index b8c507c..1599aa9 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -35,7 +35,9 @@ struct wb_writeback_work { long nr_pages; struct super_block *sb; + unsigned long *older_than_this; enum writeback_sync_modes sync_mode; + unsigned int tagged_writepages:1; unsigned int for_kupdate:1; unsigned int range_cyclic:1; unsigned int for_background:1; @@ -180,12 +182,13 @@ void bdi_start_background_writeback(struct backing_dev_info *bdi) */ void inode_wb_list_del(struct inode *inode) { - spin_lock(&inode_wb_list_lock); + struct backing_dev_info *bdi = inode_to_bdi(inode); + + spin_lock(&bdi->wb.list_lock); list_del_init(&inode->i_wb_list); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&bdi->wb.list_lock); } - /* * Redirty an inode: set its when-it-was dirtied timestamp and move it to the * furthest end of its superblock's dirty-inode list. @@ -195,11 +198,9 @@ void inode_wb_list_del(struct inode *inode) * the case then the inode must have been redirtied while it was being written * out and we don't reset its dirtied_when. */ -static void redirty_tail(struct inode *inode) +static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) { - struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; - - assert_spin_locked(&inode_wb_list_lock); + assert_spin_locked(&wb->list_lock); if (!list_empty(&wb->b_dirty)) { struct inode *tail; @@ -213,11 +214,9 @@ static void redirty_tail(struct inode *inode) /* * requeue inode for re-scanning after bdi->b_io list is exhausted. */ -static void requeue_io(struct inode *inode) +static void requeue_io(struct inode *inode, struct bdi_writeback *wb) { - struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; - - assert_spin_locked(&inode_wb_list_lock); + assert_spin_locked(&wb->list_lock); list_move(&inode->i_wb_list, &wb->b_more_io); } @@ -225,7 +224,7 @@ static void inode_sync_complete(struct inode *inode) { /* * Prevent speculative execution through - * spin_unlock(&inode_wb_list_lock); + * spin_unlock(&wb->list_lock); */ smp_mb(); @@ -250,15 +249,16 @@ static bool inode_dirtied_after(struct inode *inode, unsigned long t) /* * Move expired dirty inodes from @delaying_queue to @dispatch_queue. */ -static void move_expired_inodes(struct list_head *delaying_queue, +static int move_expired_inodes(struct list_head *delaying_queue, struct list_head *dispatch_queue, - unsigned long *older_than_this) + unsigned long *older_than_this) { LIST_HEAD(tmp); struct list_head *pos, *node; struct super_block *sb = NULL; struct inode *inode; int do_sb_sort = 0; + int moved = 0; while (!list_empty(delaying_queue)) { inode = wb_inode(delaying_queue->prev); @@ -269,12 +269,13 @@ static void move_expired_inodes(struct list_head *delaying_queue, do_sb_sort = 1; sb = inode->i_sb; list_move(&inode->i_wb_list, &tmp); + moved++; } /* just one sb in list, splice to dispatch_queue and we're done */ if (!do_sb_sort) { list_splice(&tmp, dispatch_queue); - return; + goto out; } /* Move inodes from one superblock together */ @@ -286,6 +287,8 @@ static void move_expired_inodes(struct list_head *delaying_queue, list_move(&inode->i_wb_list, dispatch_queue); } } +out: + return moved; } /* @@ -301,9 +304,11 @@ static void move_expired_inodes(struct list_head *delaying_queue, */ static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) { - assert_spin_locked(&inode_wb_list_lock); + int moved; + assert_spin_locked(&wb->list_lock); list_splice_init(&wb->b_more_io, &wb->b_io); - move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); + moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); + trace_writeback_queue_io(wb, older_than_this, moved); } static int write_inode(struct inode *inode, struct writeback_control *wbc) @@ -316,7 +321,8 @@ static int write_inode(struct inode *inode, struct writeback_control *wbc) /* * Wait for writeback on an inode to complete. */ -static void inode_wait_for_writeback(struct inode *inode) +static void inode_wait_for_writeback(struct inode *inode, + struct bdi_writeback *wb) { DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); wait_queue_head_t *wqh; @@ -324,15 +330,15 @@ static void inode_wait_for_writeback(struct inode *inode) wqh = bit_waitqueue(&inode->i_state, __I_SYNC); while (inode->i_state & I_SYNC) { spin_unlock(&inode->i_lock); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&wb->list_lock); __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); - spin_lock(&inode_wb_list_lock); + spin_lock(&wb->list_lock); spin_lock(&inode->i_lock); } } /* - * Write out an inode's dirty pages. Called under inode_wb_list_lock and + * Write out an inode's dirty pages. Called under wb->list_lock and * inode->i_lock. Either the caller has an active reference on the inode or * the inode has I_WILL_FREE set. * @@ -343,13 +349,15 @@ static void inode_wait_for_writeback(struct inode *inode) * livelocks, etc. */ static int -writeback_single_inode(struct inode *inode, struct writeback_control *wbc) +writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, + struct writeback_control *wbc) { struct address_space *mapping = inode->i_mapping; + long nr_to_write = wbc->nr_to_write; unsigned dirty; int ret; - assert_spin_locked(&inode_wb_list_lock); + assert_spin_locked(&wb->list_lock); assert_spin_locked(&inode->i_lock); if (!atomic_read(&inode->i_count)) @@ -367,14 +375,16 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * completed a full scan of b_io. */ if (wbc->sync_mode != WB_SYNC_ALL) { - requeue_io(inode); + requeue_io(inode, wb); + trace_writeback_single_inode_requeue(inode, wbc, + nr_to_write); return 0; } /* * It's a data-integrity sync. We must wait. */ - inode_wait_for_writeback(inode); + inode_wait_for_writeback(inode, wb); } BUG_ON(inode->i_state & I_SYNC); @@ -383,7 +393,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) inode->i_state |= I_SYNC; inode->i_state &= ~I_DIRTY_PAGES; spin_unlock(&inode->i_lock); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&wb->list_lock); ret = do_writepages(mapping, wbc); @@ -414,10 +424,19 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) ret = err; } - spin_lock(&inode_wb_list_lock); + spin_lock(&wb->list_lock); spin_lock(&inode->i_lock); inode->i_state &= ~I_SYNC; if (!(inode->i_state & I_FREEING)) { + /* + * Sync livelock prevention. Each inode is tagged and synced in + * one shot. If still dirty, it will be redirty_tail()'ed below. + * Update the dirty time to prevent enqueue and sync it again. + */ + if ((inode->i_state & I_DIRTY) && + (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) + inode->dirtied_when = jiffies; + if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { /* * We didn't write back all the pages. nfs_writepages() @@ -428,7 +447,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) /* * slice used up: queue for next turn */ - requeue_io(inode); + requeue_io(inode, wb); } else { /* * Writeback blocked by something other than @@ -437,7 +456,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * retrying writeback of the dirty page/inode * that cannot be performed immediately. */ - redirty_tail(inode); + redirty_tail(inode, wb); } } else if (inode->i_state & I_DIRTY) { /* @@ -446,7 +465,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * submission or metadata updates after data IO * completion. */ - redirty_tail(inode); + redirty_tail(inode, wb); } else { /* * The inode is clean. At this point we either have @@ -457,9 +476,41 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) } } inode_sync_complete(inode); + trace_writeback_single_inode(inode, wbc, nr_to_write); return ret; } +static long writeback_chunk_size(struct backing_dev_info *bdi, + struct wb_writeback_work *work) +{ + long pages; + + /* + * WB_SYNC_ALL mode does livelock avoidance by syncing dirty + * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX + * here avoids calling into writeback_inodes_wb() more than once. + * + * The intended call sequence for WB_SYNC_ALL writeback is: + * + * wb_writeback() + * writeback_sb_inodes() <== called only once + * write_cache_pages() <== called once for each inode + * (quickly) tag currently dirty pages + * (maybe slowly) sync all tagged pages + */ + if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) + pages = LONG_MAX; + else { + pages = min(bdi->avg_write_bandwidth / 2, + global_dirty_limit / DIRTY_SCOPE); + pages = min(pages, work->nr_pages); + pages = round_down(pages + MIN_WRITEBACK_PAGES, + MIN_WRITEBACK_PAGES); + } + + return pages; +} + /* * Write a portion of b_io inodes which belong to @sb. * @@ -467,24 +518,36 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * inodes. Otherwise write only ones which go sequentially * in reverse order. * - * Return 1, if the caller writeback routine should be - * interrupted. Otherwise return 0. + * Return the number of pages and/or inodes written. */ -static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, - struct writeback_control *wbc, bool only_this_sb) +static long writeback_sb_inodes(struct super_block *sb, + struct bdi_writeback *wb, + struct wb_writeback_work *work) { + struct writeback_control wbc = { + .sync_mode = work->sync_mode, + .tagged_writepages = work->tagged_writepages, + .for_kupdate = work->for_kupdate, + .for_background = work->for_background, + .range_cyclic = work->range_cyclic, + .range_start = 0, + .range_end = LLONG_MAX, + }; + unsigned long start_time = jiffies; + long write_chunk; + long wrote = 0; /* count both pages and inodes */ + while (!list_empty(&wb->b_io)) { - long pages_skipped; struct inode *inode = wb_inode(wb->b_io.prev); if (inode->i_sb != sb) { - if (only_this_sb) { + if (work->sb) { /* * We only want to write back data for this * superblock, move all inodes not belonging * to it back onto the dirty list. */ - redirty_tail(inode); + redirty_tail(inode, wb); continue; } @@ -493,7 +556,7 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, * Bounce back to the caller to unpin this and * pin the next superblock. */ - return 0; + break; } /* @@ -504,95 +567,91 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, spin_lock(&inode->i_lock); if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { spin_unlock(&inode->i_lock); - requeue_io(inode); + redirty_tail(inode, wb); continue; } - - /* - * Was this inode dirtied after sync_sb_inodes was called? - * This keeps sync from extra jobs and livelock. - */ - if (inode_dirtied_after(inode, wbc->wb_start)) { - spin_unlock(&inode->i_lock); - return 1; - } - __iget(inode); + write_chunk = writeback_chunk_size(wb->bdi, work); + wbc.nr_to_write = write_chunk; + wbc.pages_skipped = 0; - pages_skipped = wbc->pages_skipped; - writeback_single_inode(inode, wbc); - if (wbc->pages_skipped != pages_skipped) { + writeback_single_inode(inode, wb, &wbc); + + work->nr_pages -= write_chunk - wbc.nr_to_write; + wrote += write_chunk - wbc.nr_to_write; + if (!(inode->i_state & I_DIRTY)) + wrote++; + if (wbc.pages_skipped) { /* * writeback is not making progress due to locked * buffers. Skip this inode for now. */ - redirty_tail(inode); + redirty_tail(inode, wb); } spin_unlock(&inode->i_lock); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&wb->list_lock); iput(inode); cond_resched(); - spin_lock(&inode_wb_list_lock); - if (wbc->nr_to_write <= 0) { - wbc->more_io = 1; - return 1; + spin_lock(&wb->list_lock); + /* + * bail out to wb_writeback() often enough to check + * background threshold and other termination conditions. + */ + if (wrote) { + if (time_is_before_jiffies(start_time + HZ / 10UL)) + break; + if (work->nr_pages <= 0) + break; } - if (!list_empty(&wb->b_more_io)) - wbc->more_io = 1; } - /* b_io is empty */ - return 1; + return wrote; } -void writeback_inodes_wb(struct bdi_writeback *wb, - struct writeback_control *wbc) +static long __writeback_inodes_wb(struct bdi_writeback *wb, + struct wb_writeback_work *work) { - int ret = 0; - - if (!wbc->wb_start) - wbc->wb_start = jiffies; /* livelock avoidance */ - spin_lock(&inode_wb_list_lock); - if (!wbc->for_kupdate || list_empty(&wb->b_io)) - queue_io(wb, wbc->older_than_this); + unsigned long start_time = jiffies; + long wrote = 0; while (!list_empty(&wb->b_io)) { struct inode *inode = wb_inode(wb->b_io.prev); struct super_block *sb = inode->i_sb; if (!grab_super_passive(sb)) { - requeue_io(inode); + requeue_io(inode, wb); continue; } - ret = writeback_sb_inodes(sb, wb, wbc, false); + wrote += writeback_sb_inodes(sb, wb, work); drop_super(sb); - if (ret) - break; + /* refer to the same tests at the end of writeback_sb_inodes */ + if (wrote) { + if (time_is_before_jiffies(start_time + HZ / 10UL)) + break; + if (work->nr_pages <= 0) + break; + } } - spin_unlock(&inode_wb_list_lock); /* Leave any unwritten inodes on b_io */ + return wrote; } -static void __writeback_inodes_sb(struct super_block *sb, - struct bdi_writeback *wb, struct writeback_control *wbc) +long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages) { - WARN_ON(!rwsem_is_locked(&sb->s_umount)); + struct wb_writeback_work work = { + .nr_pages = nr_pages, + .sync_mode = WB_SYNC_NONE, + .range_cyclic = 1, + }; - spin_lock(&inode_wb_list_lock); - if (!wbc->for_kupdate || list_empty(&wb->b_io)) - queue_io(wb, wbc->older_than_this); - writeback_sb_inodes(sb, wb, wbc, true); - spin_unlock(&inode_wb_list_lock); -} + spin_lock(&wb->list_lock); + if (list_empty(&wb->b_io)) + queue_io(wb, NULL); + __writeback_inodes_wb(wb, &work); + spin_unlock(&wb->list_lock); -/* - * The maximum number of pages to writeout in a single bdi flush/kupdate - * operation. We do this so we don't hold I_SYNC against an inode for - * enormous amounts of time, which would block a userspace task which has - * been forced to throttle against that inode. Also, the code reevaluates - * the dirty each time it has written this many pages. - */ -#define MAX_WRITEBACK_PAGES 1024 + return nr_pages - work.nr_pages; +} static inline bool over_bground_thresh(void) { @@ -605,6 +664,16 @@ static inline bool over_bground_thresh(void) } /* + * Called under wb->list_lock. If there are multiple wb per bdi, + * only the flusher working on the first wb should do it. + */ +static void wb_update_bandwidth(struct bdi_writeback *wb, + unsigned long start_time) +{ + __bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, start_time); +} + +/* * Explicit flushing or periodic writeback of "old" data. * * Define "old": the first time one of an inode's pages is dirtied, we mark the @@ -622,47 +691,16 @@ static inline bool over_bground_thresh(void) static long wb_writeback(struct bdi_writeback *wb, struct wb_writeback_work *work) { - struct writeback_control wbc = { - .sync_mode = work->sync_mode, - .older_than_this = NULL, - .for_kupdate = work->for_kupdate, - .for_background = work->for_background, - .range_cyclic = work->range_cyclic, - }; + unsigned long wb_start = jiffies; + long nr_pages = work->nr_pages; unsigned long oldest_jif; - long wrote = 0; - long write_chunk; struct inode *inode; + long progress; - if (wbc.for_kupdate) { - wbc.older_than_this = &oldest_jif; - oldest_jif = jiffies - - msecs_to_jiffies(dirty_expire_interval * 10); - } - if (!wbc.range_cyclic) { - wbc.range_start = 0; - wbc.range_end = LLONG_MAX; - } + oldest_jif = jiffies; + work->older_than_this = &oldest_jif; - /* - * WB_SYNC_ALL mode does livelock avoidance by syncing dirty - * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX - * here avoids calling into writeback_inodes_wb() more than once. - * - * The intended call sequence for WB_SYNC_ALL writeback is: - * - * wb_writeback() - * __writeback_inodes_sb() <== called only once - * write_cache_pages() <== called once for each inode - * (quickly) tag currently dirty pages - * (maybe slowly) sync all tagged pages - */ - if (wbc.sync_mode == WB_SYNC_NONE) - write_chunk = MAX_WRITEBACK_PAGES; - else - write_chunk = LONG_MAX; - - wbc.wb_start = jiffies; /* livelock avoidance */ + spin_lock(&wb->list_lock); for (;;) { /* * Stop writeback when nr_pages has been consumed @@ -687,52 +725,54 @@ static long wb_writeback(struct bdi_writeback *wb, if (work->for_background && !over_bground_thresh()) break; - wbc.more_io = 0; - wbc.nr_to_write = write_chunk; - wbc.pages_skipped = 0; + if (work->for_kupdate) { + oldest_jif = jiffies - + msecs_to_jiffies(dirty_expire_interval * 10); + work->older_than_this = &oldest_jif; + } - trace_wbc_writeback_start(&wbc, wb->bdi); + trace_writeback_start(wb->bdi, work); + if (list_empty(&wb->b_io)) + queue_io(wb, work->older_than_this); if (work->sb) - __writeback_inodes_sb(work->sb, wb, &wbc); + progress = writeback_sb_inodes(work->sb, wb, work); else - writeback_inodes_wb(wb, &wbc); - trace_wbc_writeback_written(&wbc, wb->bdi); + progress = __writeback_inodes_wb(wb, work); + trace_writeback_written(wb->bdi, work); - work->nr_pages -= write_chunk - wbc.nr_to_write; - wrote += write_chunk - wbc.nr_to_write; + wb_update_bandwidth(wb, wb_start); /* - * If we consumed everything, see if we have more + * Did we write something? Try for more + * + * Dirty inodes are moved to b_io for writeback in batches. + * The completion of the current batch does not necessarily + * mean the overall work is done. So we keep looping as long + * as made some progress on cleaning pages or inodes. */ - if (wbc.nr_to_write <= 0) + if (progress) continue; /* - * Didn't write everything and we don't have more IO, bail + * No more inodes for IO, bail */ - if (!wbc.more_io) + if (list_empty(&wb->b_more_io)) break; /* - * Did we write something? Try for more - */ - if (wbc.nr_to_write < write_chunk) - continue; - /* * Nothing written. Wait for some inode to * become available for writeback. Otherwise * we'll just busyloop. */ - spin_lock(&inode_wb_list_lock); if (!list_empty(&wb->b_more_io)) { + trace_writeback_wait(wb->bdi, work); inode = wb_inode(wb->b_more_io.prev); - trace_wbc_writeback_wait(&wbc, wb->bdi); spin_lock(&inode->i_lock); - inode_wait_for_writeback(inode); + inode_wait_for_writeback(inode, wb); spin_unlock(&inode->i_lock); } - spin_unlock(&inode_wb_list_lock); } + spin_unlock(&wb->list_lock); - return wrote; + return nr_pages - work->nr_pages; } /* @@ -1063,10 +1103,10 @@ void __mark_inode_dirty(struct inode *inode, int flags) } spin_unlock(&inode->i_lock); - spin_lock(&inode_wb_list_lock); + spin_lock(&bdi->wb.list_lock); inode->dirtied_when = jiffies; list_move(&inode->i_wb_list, &bdi->wb.b_dirty); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&bdi->wb.list_lock); if (wakeup_bdi) bdi_wakeup_thread_delayed(bdi); @@ -1162,10 +1202,11 @@ void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr) { DECLARE_COMPLETION_ONSTACK(done); struct wb_writeback_work work = { - .sb = sb, - .sync_mode = WB_SYNC_NONE, - .done = &done, - .nr_pages = nr, + .sb = sb, + .sync_mode = WB_SYNC_NONE, + .tagged_writepages = 1, + .done = &done, + .nr_pages = nr, }; WARN_ON(!rwsem_is_locked(&sb->s_umount)); @@ -1267,6 +1308,7 @@ EXPORT_SYMBOL(sync_inodes_sb); */ int write_inode_now(struct inode *inode, int sync) { + struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; int ret; struct writeback_control wbc = { .nr_to_write = LONG_MAX, @@ -1279,11 +1321,11 @@ int write_inode_now(struct inode *inode, int sync) wbc.nr_to_write = 0; might_sleep(); - spin_lock(&inode_wb_list_lock); + spin_lock(&wb->list_lock); spin_lock(&inode->i_lock); - ret = writeback_single_inode(inode, &wbc); + ret = writeback_single_inode(inode, wb, &wbc); spin_unlock(&inode->i_lock); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&wb->list_lock); if (sync) inode_sync_wait(inode); return ret; @@ -1303,13 +1345,14 @@ EXPORT_SYMBOL(write_inode_now); */ int sync_inode(struct inode *inode, struct writeback_control *wbc) { + struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; int ret; - spin_lock(&inode_wb_list_lock); + spin_lock(&wb->list_lock); spin_lock(&inode->i_lock); - ret = writeback_single_inode(inode, wbc); + ret = writeback_single_inode(inode, wb, wbc); spin_unlock(&inode->i_lock); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&wb->list_lock); return ret; } EXPORT_SYMBOL(sync_inode); @@ -37,7 +37,7 @@ * inode->i_sb->s_inode_lru, inode->i_lru * inode_sb_list_lock protects: * sb->s_inodes, inode->i_sb_list - * inode_wb_list_lock protects: + * bdi->wb.list_lock protects: * bdi->wb.b_{dirty,io,more_io}, inode->i_wb_list * inode_hash_lock protects: * inode_hashtable, inode->i_hash @@ -48,7 +48,7 @@ * inode->i_lock * inode->i_sb->s_inode_lru_lock * - * inode_wb_list_lock + * bdi->wb.list_lock * inode->i_lock * * inode_hash_lock @@ -65,7 +65,6 @@ static struct hlist_head *inode_hashtable __read_mostly; static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock); __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_sb_list_lock); -__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_wb_list_lock); /* * Empty aops. Can be used for the cases where the user does not diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 0857931..00e3750 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1566,8 +1566,7 @@ int nfs_write_inode(struct inode *inode, struct writeback_control *wbc) int status; bool sync = true; - if (wbc->sync_mode == WB_SYNC_NONE || wbc->nonblocking || - wbc->for_background) + if (wbc->sync_mode == WB_SYNC_NONE) sync = false; status = pnfs_layoutcommit_inode(inode, sync); diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 96f4094..a008982 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -40,6 +40,7 @@ typedef int (congested_fn)(void *, int); enum bdi_stat_item { BDI_RECLAIMABLE, BDI_WRITEBACK, + BDI_WRITTEN, NR_BDI_STAT_ITEMS }; @@ -57,6 +58,7 @@ struct bdi_writeback { struct list_head b_dirty; /* dirty inodes */ struct list_head b_io; /* parked for writeback */ struct list_head b_more_io; /* parked for more writeback */ + spinlock_t list_lock; /* protects the b_* lists */ }; struct backing_dev_info { @@ -71,6 +73,11 @@ struct backing_dev_info { struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; + unsigned long bw_time_stamp; /* last time write bw is updated */ + unsigned long written_stamp; /* pages written at bw_time_stamp */ + unsigned long write_bandwidth; /* the estimated write bandwidth */ + unsigned long avg_write_bandwidth; /* further smoothed write bw */ + struct prop_local_percpu completions; int dirty_exceeded; @@ -106,6 +113,7 @@ int bdi_writeback_thread(void *data); int bdi_has_dirty_io(struct backing_dev_info *bdi); void bdi_arm_supers_timer(void); void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi); +void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2); extern spinlock_t bdi_lock; extern struct list_head bdi_list; diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 17e7ccc..f1bfa12e 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -7,9 +7,39 @@ #include <linux/sched.h> #include <linux/fs.h> -struct backing_dev_info; +/* + * The 1/4 region under the global dirty thresh is for smooth dirty throttling: + * + * (thresh - thresh/DIRTY_FULL_SCOPE, thresh) + * + * The 1/16 region above the global dirty limit will be put to maximum pauses: + * + * (limit, limit + limit/DIRTY_MAXPAUSE_AREA) + * + * The 1/16 region above the max-pause region, dirty exceeded bdi's will be put + * to loops: + * + * (limit + limit/DIRTY_MAXPAUSE_AREA, limit + limit/DIRTY_PASSGOOD_AREA) + * + * Further beyond, all dirtier tasks will enter a loop waiting (possibly long + * time) for the dirty pages to drop, unless written enough pages. + * + * The global dirty threshold is normally equal to the global dirty limit, + * except when the system suddenly allocates a lot of anonymous memory and + * knocks down the global dirty threshold quickly, in which case the global + * dirty limit will follow down slowly to prevent livelocking all dirtier tasks. + */ +#define DIRTY_SCOPE 8 +#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2) +#define DIRTY_MAXPAUSE_AREA 16 +#define DIRTY_PASSGOOD_AREA 8 -extern spinlock_t inode_wb_list_lock; +/* + * 4MB minimal write chunk size + */ +#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10)) + +struct backing_dev_info; /* * fs/fs-writeback.c @@ -26,11 +56,6 @@ enum writeback_sync_modes { */ struct writeback_control { enum writeback_sync_modes sync_mode; - unsigned long *older_than_this; /* If !NULL, only write back inodes - older than this */ - unsigned long wb_start; /* Time writeback_inodes_wb was - called. This is needed to avoid - extra jobs and livelock */ long nr_to_write; /* Write this many pages, and decrement this for each page written */ long pages_skipped; /* Pages which were not written */ @@ -43,13 +68,11 @@ struct writeback_control { loff_t range_start; loff_t range_end; - unsigned nonblocking:1; /* Don't get stuck on request queues */ - unsigned encountered_congestion:1; /* An output: a queue is full */ unsigned for_kupdate:1; /* A kupdate writeback */ unsigned for_background:1; /* A background writeback */ + unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */ unsigned for_reclaim:1; /* Invoked from the page allocator */ unsigned range_cyclic:1; /* range_start is cyclic */ - unsigned more_io:1; /* more io to be dispatched */ }; /* @@ -62,8 +85,7 @@ void writeback_inodes_sb_nr(struct super_block *, unsigned long nr); int writeback_inodes_sb_if_idle(struct super_block *); int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr); void sync_inodes_sb(struct super_block *); -void writeback_inodes_wb(struct bdi_writeback *wb, - struct writeback_control *wbc); +long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages); long wb_do_writeback(struct bdi_writeback *wb, int force_wait); void wakeup_flusher_threads(long nr_pages); @@ -94,6 +116,8 @@ static inline void laptop_sync_completion(void) { } #endif void throttle_vm_writeout(gfp_t gfp_mask); +extern unsigned long global_dirty_limit; + /* These are exported to sysctl. */ extern int dirty_background_ratio; extern unsigned long dirty_background_bytes; @@ -128,6 +152,13 @@ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, unsigned long dirty); +void __bdi_update_bandwidth(struct backing_dev_info *bdi, + unsigned long thresh, + unsigned long dirty, + unsigned long bdi_thresh, + unsigned long bdi_dirty, + unsigned long start_time); + void page_writeback_init(void); void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, unsigned long nr_pages_dirtied); diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h index 4114129..b31702a 100644 --- a/include/trace/events/btrfs.h +++ b/include/trace/events/btrfs.h @@ -284,7 +284,6 @@ DECLARE_EVENT_CLASS(btrfs__writepage, __field( long, pages_skipped ) __field( loff_t, range_start ) __field( loff_t, range_end ) - __field( char, nonblocking ) __field( char, for_kupdate ) __field( char, for_reclaim ) __field( char, range_cyclic ) @@ -299,7 +298,6 @@ DECLARE_EVENT_CLASS(btrfs__writepage, __entry->pages_skipped = wbc->pages_skipped; __entry->range_start = wbc->range_start; __entry->range_end = wbc->range_end; - __entry->nonblocking = wbc->nonblocking; __entry->for_kupdate = wbc->for_kupdate; __entry->for_reclaim = wbc->for_reclaim; __entry->range_cyclic = wbc->range_cyclic; @@ -310,13 +308,13 @@ DECLARE_EVENT_CLASS(btrfs__writepage, TP_printk("root = %llu(%s), ino = %lu, page_index = %lu, " "nr_to_write = %ld, pages_skipped = %ld, range_start = %llu, " - "range_end = %llu, nonblocking = %d, for_kupdate = %d, " + "range_end = %llu, for_kupdate = %d, " "for_reclaim = %d, range_cyclic = %d, writeback_index = %lu", show_root_type(__entry->root_objectid), (unsigned long)__entry->ino, __entry->index, __entry->nr_to_write, __entry->pages_skipped, __entry->range_start, __entry->range_end, - __entry->nonblocking, __entry->for_kupdate, + __entry->for_kupdate, __entry->for_reclaim, __entry->range_cyclic, (unsigned long)__entry->writeback_index) ); diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h index 5ce2b2f..6363193 100644 --- a/include/trace/events/ext4.h +++ b/include/trace/events/ext4.h @@ -380,7 +380,6 @@ TRACE_EVENT(ext4_da_writepages_result, __field( int, pages_written ) __field( long, pages_skipped ) __field( int, sync_mode ) - __field( char, more_io ) __field( pgoff_t, writeback_index ) ), @@ -391,16 +390,15 @@ TRACE_EVENT(ext4_da_writepages_result, __entry->pages_written = pages_written; __entry->pages_skipped = wbc->pages_skipped; __entry->sync_mode = wbc->sync_mode; - __entry->more_io = wbc->more_io; __entry->writeback_index = inode->i_mapping->writeback_index; ), TP_printk("dev %d,%d ino %lu ret %d pages_written %d pages_skipped %ld " - " more_io %d sync_mode %d writeback_index %lu", + "sync_mode %d writeback_index %lu", MAJOR(__entry->dev), MINOR(__entry->dev), (unsigned long) __entry->ino, __entry->ret, __entry->pages_written, __entry->pages_skipped, - __entry->more_io, __entry->sync_mode, + __entry->sync_mode, (unsigned long) __entry->writeback_index) ); diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 4e249b9..6bca4cc 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -8,6 +8,19 @@ #include <linux/device.h> #include <linux/writeback.h> +#define show_inode_state(state) \ + __print_flags(state, "|", \ + {I_DIRTY_SYNC, "I_DIRTY_SYNC"}, \ + {I_DIRTY_DATASYNC, "I_DIRTY_DATASYNC"}, \ + {I_DIRTY_PAGES, "I_DIRTY_PAGES"}, \ + {I_NEW, "I_NEW"}, \ + {I_WILL_FREE, "I_WILL_FREE"}, \ + {I_FREEING, "I_FREEING"}, \ + {I_CLEAR, "I_CLEAR"}, \ + {I_SYNC, "I_SYNC"}, \ + {I_REFERENCED, "I_REFERENCED"} \ + ) + struct wb_writeback_work; DECLARE_EVENT_CLASS(writeback_work_class, @@ -49,6 +62,9 @@ DEFINE_EVENT(writeback_work_class, name, \ DEFINE_WRITEBACK_WORK_EVENT(writeback_nothread); DEFINE_WRITEBACK_WORK_EVENT(writeback_queue); DEFINE_WRITEBACK_WORK_EVENT(writeback_exec); +DEFINE_WRITEBACK_WORK_EVENT(writeback_start); +DEFINE_WRITEBACK_WORK_EVENT(writeback_written); +DEFINE_WRITEBACK_WORK_EVENT(writeback_wait); TRACE_EVENT(writeback_pages_written, TP_PROTO(long pages_written), @@ -88,6 +104,30 @@ DEFINE_WRITEBACK_EVENT(writeback_bdi_register); DEFINE_WRITEBACK_EVENT(writeback_bdi_unregister); DEFINE_WRITEBACK_EVENT(writeback_thread_start); DEFINE_WRITEBACK_EVENT(writeback_thread_stop); +DEFINE_WRITEBACK_EVENT(balance_dirty_start); +DEFINE_WRITEBACK_EVENT(balance_dirty_wait); + +TRACE_EVENT(balance_dirty_written, + + TP_PROTO(struct backing_dev_info *bdi, int written), + + TP_ARGS(bdi, written), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(int, written) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(bdi->dev), 32); + __entry->written = written; + ), + + TP_printk("bdi %s written %d", + __entry->name, + __entry->written + ) +); DECLARE_EVENT_CLASS(wbc_class, TP_PROTO(struct writeback_control *wbc, struct backing_dev_info *bdi), @@ -101,8 +141,6 @@ DECLARE_EVENT_CLASS(wbc_class, __field(int, for_background) __field(int, for_reclaim) __field(int, range_cyclic) - __field(int, more_io) - __field(unsigned long, older_than_this) __field(long, range_start) __field(long, range_end) ), @@ -116,15 +154,12 @@ DECLARE_EVENT_CLASS(wbc_class, __entry->for_background = wbc->for_background; __entry->for_reclaim = wbc->for_reclaim; __entry->range_cyclic = wbc->range_cyclic; - __entry->more_io = wbc->more_io; - __entry->older_than_this = wbc->older_than_this ? - *wbc->older_than_this : 0; __entry->range_start = (long)wbc->range_start; __entry->range_end = (long)wbc->range_end; ), TP_printk("bdi %s: towrt=%ld skip=%ld mode=%d kupd=%d " - "bgrd=%d reclm=%d cyclic=%d more=%d older=0x%lx " + "bgrd=%d reclm=%d cyclic=%d " "start=0x%lx end=0x%lx", __entry->name, __entry->nr_to_write, @@ -134,8 +169,6 @@ DECLARE_EVENT_CLASS(wbc_class, __entry->for_background, __entry->for_reclaim, __entry->range_cyclic, - __entry->more_io, - __entry->older_than_this, __entry->range_start, __entry->range_end) ) @@ -144,14 +177,79 @@ DECLARE_EVENT_CLASS(wbc_class, DEFINE_EVENT(wbc_class, name, \ TP_PROTO(struct writeback_control *wbc, struct backing_dev_info *bdi), \ TP_ARGS(wbc, bdi)) -DEFINE_WBC_EVENT(wbc_writeback_start); -DEFINE_WBC_EVENT(wbc_writeback_written); -DEFINE_WBC_EVENT(wbc_writeback_wait); -DEFINE_WBC_EVENT(wbc_balance_dirty_start); -DEFINE_WBC_EVENT(wbc_balance_dirty_written); -DEFINE_WBC_EVENT(wbc_balance_dirty_wait); DEFINE_WBC_EVENT(wbc_writepage); +TRACE_EVENT(writeback_queue_io, + TP_PROTO(struct bdi_writeback *wb, + unsigned long *older_than_this, + int moved), + TP_ARGS(wb, older_than_this, moved), + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned long, older) + __field(long, age) + __field(int, moved) + ), + TP_fast_assign( + strncpy(__entry->name, dev_name(wb->bdi->dev), 32); + __entry->older = older_than_this ? *older_than_this : 0; + __entry->age = older_than_this ? + (jiffies - *older_than_this) * 1000 / HZ : -1; + __entry->moved = moved; + ), + TP_printk("bdi %s: older=%lu age=%ld enqueue=%d", + __entry->name, + __entry->older, /* older_than_this in jiffies */ + __entry->age, /* older_than_this in relative milliseconds */ + __entry->moved) +); + +TRACE_EVENT(global_dirty_state, + + TP_PROTO(unsigned long background_thresh, + unsigned long dirty_thresh + ), + + TP_ARGS(background_thresh, + dirty_thresh + ), + + TP_STRUCT__entry( + __field(unsigned long, nr_dirty) + __field(unsigned long, nr_writeback) + __field(unsigned long, nr_unstable) + __field(unsigned long, background_thresh) + __field(unsigned long, dirty_thresh) + __field(unsigned long, dirty_limit) + __field(unsigned long, nr_dirtied) + __field(unsigned long, nr_written) + ), + + TP_fast_assign( + __entry->nr_dirty = global_page_state(NR_FILE_DIRTY); + __entry->nr_writeback = global_page_state(NR_WRITEBACK); + __entry->nr_unstable = global_page_state(NR_UNSTABLE_NFS); + __entry->nr_dirtied = global_page_state(NR_DIRTIED); + __entry->nr_written = global_page_state(NR_WRITTEN); + __entry->background_thresh = background_thresh; + __entry->dirty_thresh = dirty_thresh; + __entry->dirty_limit = global_dirty_limit; + ), + + TP_printk("dirty=%lu writeback=%lu unstable=%lu " + "bg_thresh=%lu thresh=%lu limit=%lu " + "dirtied=%lu written=%lu", + __entry->nr_dirty, + __entry->nr_writeback, + __entry->nr_unstable, + __entry->background_thresh, + __entry->dirty_thresh, + __entry->dirty_limit, + __entry->nr_dirtied, + __entry->nr_written + ) +); + DECLARE_EVENT_CLASS(writeback_congest_waited_template, TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed), @@ -187,6 +285,63 @@ DEFINE_EVENT(writeback_congest_waited_template, writeback_wait_iff_congested, TP_ARGS(usec_timeout, usec_delayed) ); +DECLARE_EVENT_CLASS(writeback_single_inode_template, + + TP_PROTO(struct inode *inode, + struct writeback_control *wbc, + unsigned long nr_to_write + ), + + TP_ARGS(inode, wbc, nr_to_write), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned long, ino) + __field(unsigned long, state) + __field(unsigned long, age) + __field(unsigned long, writeback_index) + __field(long, nr_to_write) + __field(unsigned long, wrote) + ), + + TP_fast_assign( + strncpy(__entry->name, + dev_name(inode->i_mapping->backing_dev_info->dev), 32); + __entry->ino = inode->i_ino; + __entry->state = inode->i_state; + __entry->age = (jiffies - inode->dirtied_when) * + 1000 / HZ; + __entry->writeback_index = inode->i_mapping->writeback_index; + __entry->nr_to_write = nr_to_write; + __entry->wrote = nr_to_write - wbc->nr_to_write; + ), + + TP_printk("bdi %s: ino=%lu state=%s age=%lu " + "index=%lu to_write=%ld wrote=%lu", + __entry->name, + __entry->ino, + show_inode_state(__entry->state), + __entry->age, + __entry->writeback_index, + __entry->nr_to_write, + __entry->wrote + ) +); + +DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode_requeue, + TP_PROTO(struct inode *inode, + struct writeback_control *wbc, + unsigned long nr_to_write), + TP_ARGS(inode, wbc, nr_to_write) +); + +DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode, + TP_PROTO(struct inode *inode, + struct writeback_control *wbc, + unsigned long nr_to_write), + TP_ARGS(inode, wbc, nr_to_write) +); + #endif /* _TRACE_WRITEBACK_H */ /* This part must be outside protection */ diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 8290b1e..d6edf8d 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -45,6 +45,17 @@ static struct timer_list sync_supers_timer; static int bdi_sync_supers(void *); static void sync_supers_timer_fn(unsigned long); +void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2) +{ + if (wb1 < wb2) { + spin_lock(&wb1->list_lock); + spin_lock_nested(&wb2->list_lock, 1); + } else { + spin_lock(&wb2->list_lock); + spin_lock_nested(&wb1->list_lock, 1); + } +} + #ifdef CONFIG_DEBUG_FS #include <linux/debugfs.h> #include <linux/seq_file.h> @@ -67,34 +78,42 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) struct inode *inode; nr_dirty = nr_io = nr_more_io = 0; - spin_lock(&inode_wb_list_lock); + spin_lock(&wb->list_lock); list_for_each_entry(inode, &wb->b_dirty, i_wb_list) nr_dirty++; list_for_each_entry(inode, &wb->b_io, i_wb_list) nr_io++; list_for_each_entry(inode, &wb->b_more_io, i_wb_list) nr_more_io++; - spin_unlock(&inode_wb_list_lock); + spin_unlock(&wb->list_lock); global_dirty_limits(&background_thresh, &dirty_thresh); bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); #define K(x) ((x) << (PAGE_SHIFT - 10)) seq_printf(m, - "BdiWriteback: %8lu kB\n" - "BdiReclaimable: %8lu kB\n" - "BdiDirtyThresh: %8lu kB\n" - "DirtyThresh: %8lu kB\n" - "BackgroundThresh: %8lu kB\n" - "b_dirty: %8lu\n" - "b_io: %8lu\n" - "b_more_io: %8lu\n" - "bdi_list: %8u\n" - "state: %8lx\n", + "BdiWriteback: %10lu kB\n" + "BdiReclaimable: %10lu kB\n" + "BdiDirtyThresh: %10lu kB\n" + "DirtyThresh: %10lu kB\n" + "BackgroundThresh: %10lu kB\n" + "BdiWritten: %10lu kB\n" + "BdiWriteBandwidth: %10lu kBps\n" + "b_dirty: %10lu\n" + "b_io: %10lu\n" + "b_more_io: %10lu\n" + "bdi_list: %10u\n" + "state: %10lx\n", (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), - K(bdi_thresh), K(dirty_thresh), - K(background_thresh), nr_dirty, nr_io, nr_more_io, + K(bdi_thresh), + K(dirty_thresh), + K(background_thresh), + (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)), + (unsigned long) K(bdi->write_bandwidth), + nr_dirty, + nr_io, + nr_more_io, !list_empty(&bdi->bdi_list), bdi->state); #undef K @@ -249,18 +268,6 @@ int bdi_has_dirty_io(struct backing_dev_info *bdi) return wb_has_dirty_io(&bdi->wb); } -static void bdi_flush_io(struct backing_dev_info *bdi) -{ - struct writeback_control wbc = { - .sync_mode = WB_SYNC_NONE, - .older_than_this = NULL, - .range_cyclic = 1, - .nr_to_write = 1024, - }; - - writeback_inodes_wb(&bdi->wb, &wbc); -} - /* * kupdated() used to do this. We cannot do it from the bdi_forker_thread() * or we risk deadlocking on ->s_umount. The longer term solution would be @@ -446,9 +453,10 @@ static int bdi_forker_thread(void *ptr) if (IS_ERR(task)) { /* * If thread creation fails, force writeout of - * the bdi from the thread. + * the bdi from the thread. Hopefully 1024 is + * large enough for efficient IO. */ - bdi_flush_io(bdi); + writeback_inodes_wb(&bdi->wb, 1024); } else { /* * The spinlock makes sure we do not lose @@ -629,9 +637,15 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) INIT_LIST_HEAD(&wb->b_dirty); INIT_LIST_HEAD(&wb->b_io); INIT_LIST_HEAD(&wb->b_more_io); + spin_lock_init(&wb->list_lock); setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi); } +/* + * Initial write bandwidth: 100 MB/s + */ +#define INIT_BW (100 << (20 - PAGE_SHIFT)) + int bdi_init(struct backing_dev_info *bdi) { int i, err; @@ -654,6 +668,13 @@ int bdi_init(struct backing_dev_info *bdi) } bdi->dirty_exceeded = 0; + + bdi->bw_time_stamp = jiffies; + bdi->written_stamp = 0; + + bdi->write_bandwidth = INIT_BW; + bdi->avg_write_bandwidth = INIT_BW; + err = prop_local_init_percpu(&bdi->completions); if (err) { @@ -677,11 +698,12 @@ void bdi_destroy(struct backing_dev_info *bdi) if (bdi_has_dirty_io(bdi)) { struct bdi_writeback *dst = &default_backing_dev_info.wb; - spin_lock(&inode_wb_list_lock); + bdi_lock_two(&bdi->wb, dst); list_splice(&bdi->wb.b_dirty, &dst->b_dirty); list_splice(&bdi->wb.b_io, &dst->b_io); list_splice(&bdi->wb.b_more_io, &dst->b_more_io); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&bdi->wb.list_lock); + spin_unlock(&dst->list_lock); } bdi_unregister(bdi); diff --git a/mm/filemap.c b/mm/filemap.c index 10a1711..867d402 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -78,7 +78,7 @@ * ->i_mutex (generic_file_buffered_write) * ->mmap_sem (fault_in_pages_readable->do_page_fault) * - * inode_wb_list_lock + * bdi->wb.list_lock * sb_lock (fs/fs-writeback.c) * ->mapping->tree_lock (__sync_single_inode) * @@ -96,9 +96,9 @@ * ->zone.lru_lock (check_pte_range->isolate_lru_page) * ->private_lock (page_remove_rmap->set_page_dirty) * ->tree_lock (page_remove_rmap->set_page_dirty) - * inode_wb_list_lock (page_remove_rmap->set_page_dirty) + * bdi.wb->list_lock (page_remove_rmap->set_page_dirty) * ->inode->i_lock (page_remove_rmap->set_page_dirty) - * inode_wb_list_lock (zap_pte_range->set_page_dirty) + * bdi.wb->list_lock (zap_pte_range->set_page_dirty) * ->inode->i_lock (zap_pte_range->set_page_dirty) * ->private_lock (zap_pte_range->__set_page_dirty_buffers) * diff --git a/mm/page-writeback.c b/mm/page-writeback.c index d8767b3..d196074 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -37,6 +37,16 @@ #include <trace/events/writeback.h> /* + * Sleep at most 200ms at a time in balance_dirty_pages(). + */ +#define MAX_PAUSE max(HZ/5, 1) + +/* + * Estimate write bandwidth at 200ms intervals. + */ +#define BANDWIDTH_INTERVAL max(HZ/5, 1) + +/* * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited * will look to see if it needs to force writeback or throttling. */ @@ -111,6 +121,7 @@ EXPORT_SYMBOL(laptop_mode); /* End of sysctl-exported parameters */ +unsigned long global_dirty_limit; /* * Scale the writeback cache size proportional to the relative writeout speeds. @@ -219,6 +230,7 @@ int dirty_bytes_handler(struct ctl_table *table, int write, */ static inline void __bdi_writeout_inc(struct backing_dev_info *bdi) { + __inc_bdi_stat(bdi, BDI_WRITTEN); __prop_inc_percpu_max(&vm_completions, &bdi->completions, bdi->max_prop_frac); } @@ -244,13 +256,8 @@ void task_dirty_inc(struct task_struct *tsk) static void bdi_writeout_fraction(struct backing_dev_info *bdi, long *numerator, long *denominator) { - if (bdi_cap_writeback_dirty(bdi)) { - prop_fraction_percpu(&vm_completions, &bdi->completions, + prop_fraction_percpu(&vm_completions, &bdi->completions, numerator, denominator); - } else { - *numerator = 0; - *denominator = 1; - } } static inline void task_dirties_fraction(struct task_struct *tsk, @@ -274,12 +281,13 @@ static inline void task_dirties_fraction(struct task_struct *tsk, * effectively curb the growth of dirty pages. Light dirtiers with high enough * dirty threshold may never get throttled. */ +#define TASK_LIMIT_FRACTION 8 static unsigned long task_dirty_limit(struct task_struct *tsk, unsigned long bdi_dirty) { long numerator, denominator; unsigned long dirty = bdi_dirty; - u64 inv = dirty >> 3; + u64 inv = dirty / TASK_LIMIT_FRACTION; task_dirties_fraction(tsk, &numerator, &denominator); inv *= numerator; @@ -290,6 +298,12 @@ static unsigned long task_dirty_limit(struct task_struct *tsk, return max(dirty, bdi_dirty/2); } +/* Minimum limit for any task */ +static unsigned long task_min_dirty_limit(unsigned long bdi_dirty) +{ + return bdi_dirty - bdi_dirty / TASK_LIMIT_FRACTION; +} + /* * */ @@ -397,6 +411,11 @@ unsigned long determine_dirtyable_memory(void) return x + 1; /* Ensure that we never return 0 */ } +static unsigned long hard_dirty_limit(unsigned long thresh) +{ + return max(thresh, global_dirty_limit); +} + /* * global_dirty_limits - background-writeback and dirty-throttling thresholds * @@ -435,12 +454,20 @@ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty) } *pbackground = background; *pdirty = dirty; + trace_global_dirty_state(background, dirty); } -/* +/** * bdi_dirty_limit - @bdi's share of dirty throttling threshold + * @bdi: the backing_dev_info to query + * @dirty: global dirty limit in pages * - * Allocate high/low dirty limits to fast/slow devices, in order to prevent + * Returns @bdi's dirty limit in pages. The term "dirty" in the context of + * dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages. + * And the "limit" in the name is not seriously taken as hard limit in + * balance_dirty_pages(). + * + * It allocates high/low dirty limits to fast/slow devices, in order to prevent * - starving fast devices * - piling up dirty pages (that will take long time to sync) on slow devices * @@ -468,6 +495,153 @@ unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, unsigned long dirty) return bdi_dirty; } +static void bdi_update_write_bandwidth(struct backing_dev_info *bdi, + unsigned long elapsed, + unsigned long written) +{ + const unsigned long period = roundup_pow_of_two(3 * HZ); + unsigned long avg = bdi->avg_write_bandwidth; + unsigned long old = bdi->write_bandwidth; + u64 bw; + + /* + * bw = written * HZ / elapsed + * + * bw * elapsed + write_bandwidth * (period - elapsed) + * write_bandwidth = --------------------------------------------------- + * period + */ + bw = written - bdi->written_stamp; + bw *= HZ; + if (unlikely(elapsed > period)) { + do_div(bw, elapsed); + avg = bw; + goto out; + } + bw += (u64)bdi->write_bandwidth * (period - elapsed); + bw >>= ilog2(period); + + /* + * one more level of smoothing, for filtering out sudden spikes + */ + if (avg > old && old >= (unsigned long)bw) + avg -= (avg - old) >> 3; + + if (avg < old && old <= (unsigned long)bw) + avg += (old - avg) >> 3; + +out: + bdi->write_bandwidth = bw; + bdi->avg_write_bandwidth = avg; +} + +/* + * The global dirtyable memory and dirty threshold could be suddenly knocked + * down by a large amount (eg. on the startup of KVM in a swapless system). + * This may throw the system into deep dirty exceeded state and throttle + * heavy/light dirtiers alike. To retain good responsiveness, maintain + * global_dirty_limit for tracking slowly down to the knocked down dirty + * threshold. + */ +static void update_dirty_limit(unsigned long thresh, unsigned long dirty) +{ + unsigned long limit = global_dirty_limit; + + /* + * Follow up in one step. + */ + if (limit < thresh) { + limit = thresh; + goto update; + } + + /* + * Follow down slowly. Use the higher one as the target, because thresh + * may drop below dirty. This is exactly the reason to introduce + * global_dirty_limit which is guaranteed to lie above the dirty pages. + */ + thresh = max(thresh, dirty); + if (limit > thresh) { + limit -= (limit - thresh) >> 5; + goto update; + } + return; +update: + global_dirty_limit = limit; +} + +static void global_update_bandwidth(unsigned long thresh, + unsigned long dirty, + unsigned long now) +{ + static DEFINE_SPINLOCK(dirty_lock); + static unsigned long update_time; + + /* + * check locklessly first to optimize away locking for the most time + */ + if (time_before(now, update_time + BANDWIDTH_INTERVAL)) + return; + + spin_lock(&dirty_lock); + if (time_after_eq(now, update_time + BANDWIDTH_INTERVAL)) { + update_dirty_limit(thresh, dirty); + update_time = now; + } + spin_unlock(&dirty_lock); +} + +void __bdi_update_bandwidth(struct backing_dev_info *bdi, + unsigned long thresh, + unsigned long dirty, + unsigned long bdi_thresh, + unsigned long bdi_dirty, + unsigned long start_time) +{ + unsigned long now = jiffies; + unsigned long elapsed = now - bdi->bw_time_stamp; + unsigned long written; + + /* + * rate-limit, only update once every 200ms. + */ + if (elapsed < BANDWIDTH_INTERVAL) + return; + + written = percpu_counter_read(&bdi->bdi_stat[BDI_WRITTEN]); + + /* + * Skip quiet periods when disk bandwidth is under-utilized. + * (at least 1s idle time between two flusher runs) + */ + if (elapsed > HZ && time_before(bdi->bw_time_stamp, start_time)) + goto snapshot; + + if (thresh) + global_update_bandwidth(thresh, dirty, now); + + bdi_update_write_bandwidth(bdi, elapsed, written); + +snapshot: + bdi->written_stamp = written; + bdi->bw_time_stamp = now; +} + +static void bdi_update_bandwidth(struct backing_dev_info *bdi, + unsigned long thresh, + unsigned long dirty, + unsigned long bdi_thresh, + unsigned long bdi_dirty, + unsigned long start_time) +{ + if (time_is_after_eq_jiffies(bdi->bw_time_stamp + BANDWIDTH_INTERVAL)) + return; + spin_lock(&bdi->wb.list_lock); + __bdi_update_bandwidth(bdi, thresh, dirty, bdi_thresh, bdi_dirty, + start_time); + spin_unlock(&bdi->wb.list_lock); +} + /* * balance_dirty_pages() must be called by processes which are generating dirty * data. It looks at the number of dirty pages in the machine and will force @@ -478,27 +652,25 @@ unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, unsigned long dirty) static void balance_dirty_pages(struct address_space *mapping, unsigned long write_chunk) { - long nr_reclaimable, bdi_nr_reclaimable; - long nr_writeback, bdi_nr_writeback; + unsigned long nr_reclaimable, bdi_nr_reclaimable; + unsigned long nr_dirty; /* = file_dirty + writeback + unstable_nfs */ + unsigned long bdi_dirty; unsigned long background_thresh; unsigned long dirty_thresh; unsigned long bdi_thresh; + unsigned long task_bdi_thresh; + unsigned long min_task_bdi_thresh; unsigned long pages_written = 0; unsigned long pause = 1; bool dirty_exceeded = false; + bool clear_dirty_exceeded = true; struct backing_dev_info *bdi = mapping->backing_dev_info; + unsigned long start_time = jiffies; for (;;) { - struct writeback_control wbc = { - .sync_mode = WB_SYNC_NONE, - .older_than_this = NULL, - .nr_to_write = write_chunk, - .range_cyclic = 1, - }; - nr_reclaimable = global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS); - nr_writeback = global_page_state(NR_WRITEBACK); + nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK); global_dirty_limits(&background_thresh, &dirty_thresh); @@ -507,12 +679,12 @@ static void balance_dirty_pages(struct address_space *mapping, * catch-up. This avoids (excessively) small writeouts * when the bdi limits are ramping up. */ - if (nr_reclaimable + nr_writeback <= - (background_thresh + dirty_thresh) / 2) + if (nr_dirty <= (background_thresh + dirty_thresh) / 2) break; bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); - bdi_thresh = task_dirty_limit(current, bdi_thresh); + min_task_bdi_thresh = task_min_dirty_limit(bdi_thresh); + task_bdi_thresh = task_dirty_limit(current, bdi_thresh); /* * In order to avoid the stacked BDI deadlock we need @@ -524,12 +696,14 @@ static void balance_dirty_pages(struct address_space *mapping, * actually dirty; with m+n sitting in the percpu * deltas. */ - if (bdi_thresh < 2*bdi_stat_error(bdi)) { + if (task_bdi_thresh < 2 * bdi_stat_error(bdi)) { bdi_nr_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE); - bdi_nr_writeback = bdi_stat_sum(bdi, BDI_WRITEBACK); + bdi_dirty = bdi_nr_reclaimable + + bdi_stat_sum(bdi, BDI_WRITEBACK); } else { bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE); - bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK); + bdi_dirty = bdi_nr_reclaimable + + bdi_stat(bdi, BDI_WRITEBACK); } /* @@ -538,9 +712,10 @@ static void balance_dirty_pages(struct address_space *mapping, * bdi or process from holding back light ones; The latter is * the last resort safeguard. */ - dirty_exceeded = - (bdi_nr_reclaimable + bdi_nr_writeback > bdi_thresh) - || (nr_reclaimable + nr_writeback > dirty_thresh); + dirty_exceeded = (bdi_dirty > task_bdi_thresh) || + (nr_dirty > dirty_thresh); + clear_dirty_exceeded = (bdi_dirty <= min_task_bdi_thresh) && + (nr_dirty <= dirty_thresh); if (!dirty_exceeded) break; @@ -548,6 +723,9 @@ static void balance_dirty_pages(struct address_space *mapping, if (!bdi->dirty_exceeded) bdi->dirty_exceeded = 1; + bdi_update_bandwidth(bdi, dirty_thresh, nr_dirty, + bdi_thresh, bdi_dirty, start_time); + /* Note: nr_reclaimable denotes nr_dirty + nr_unstable. * Unstable writes are a feature of certain networked * filesystems (i.e. NFS) in which data may have been @@ -557,17 +735,40 @@ static void balance_dirty_pages(struct address_space *mapping, * threshold otherwise wait until the disk writes catch * up. */ - trace_wbc_balance_dirty_start(&wbc, bdi); - if (bdi_nr_reclaimable > bdi_thresh) { - writeback_inodes_wb(&bdi->wb, &wbc); - pages_written += write_chunk - wbc.nr_to_write; - trace_wbc_balance_dirty_written(&wbc, bdi); + trace_balance_dirty_start(bdi); + if (bdi_nr_reclaimable > task_bdi_thresh) { + pages_written += writeback_inodes_wb(&bdi->wb, + write_chunk); + trace_balance_dirty_written(bdi, pages_written); if (pages_written >= write_chunk) break; /* We've done our duty */ } - trace_wbc_balance_dirty_wait(&wbc, bdi); __set_current_state(TASK_UNINTERRUPTIBLE); io_schedule_timeout(pause); + trace_balance_dirty_wait(bdi); + + dirty_thresh = hard_dirty_limit(dirty_thresh); + /* + * max-pause area. If dirty exceeded but still within this + * area, no need to sleep for more than 200ms: (a) 8 pages per + * 200ms is typically more than enough to curb heavy dirtiers; + * (b) the pause time limit makes the dirtiers more responsive. + */ + if (nr_dirty < dirty_thresh + + dirty_thresh / DIRTY_MAXPAUSE_AREA && + time_after(jiffies, start_time + MAX_PAUSE)) + break; + /* + * pass-good area. When some bdi gets blocked (eg. NFS server + * not responding), or write bandwidth dropped dramatically due + * to concurrent reads, or dirty threshold suddenly dropped and + * the dirty pages cannot be brought down anytime soon (eg. on + * slow USB stick), at least let go of the good bdi's. + */ + if (nr_dirty < dirty_thresh + + dirty_thresh / DIRTY_PASSGOOD_AREA && + bdi_dirty < bdi_thresh) + break; /* * Increase the delay for each loop, up to our previous @@ -578,7 +779,8 @@ static void balance_dirty_pages(struct address_space *mapping, pause = HZ / 10; } - if (!dirty_exceeded && bdi->dirty_exceeded) + /* Clear dirty_exceeded flag only when no task can exceed the limit */ + if (clear_dirty_exceeded && bdi->dirty_exceeded) bdi->dirty_exceeded = 0; if (writeback_in_progress(bdi)) @@ -626,9 +828,13 @@ static DEFINE_PER_CPU(unsigned long, bdp_ratelimits) = 0; void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, unsigned long nr_pages_dirtied) { + struct backing_dev_info *bdi = mapping->backing_dev_info; unsigned long ratelimit; unsigned long *p; + if (!bdi_cap_account_dirty(bdi)) + return; + ratelimit = ratelimit_pages; if (mapping->backing_dev_info->dirty_exceeded) ratelimit = 8; @@ -892,12 +1098,12 @@ int write_cache_pages(struct address_space *mapping, range_whole = 1; cycled = 1; /* ignore range_cyclic tests */ } - if (wbc->sync_mode == WB_SYNC_ALL) + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) tag = PAGECACHE_TAG_TOWRITE; else tag = PAGECACHE_TAG_DIRTY; retry: - if (wbc->sync_mode == WB_SYNC_ALL) + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) tag_pages_for_writeback(mapping, index, end); done_index = index; while (!done && (index <= end)) { @@ -31,11 +31,11 @@ * mmlist_lock (in mmput, drain_mmlist and others) * mapping->private_lock (in __set_page_dirty_buffers) * inode->i_lock (in set_page_dirty's __mark_inode_dirty) - * inode_wb_list_lock (in set_page_dirty's __mark_inode_dirty) + * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) * sb_lock (within inode_lock in fs/fs-writeback.c) * mapping->tree_lock (widely used, in set_page_dirty, * in arch-dependent flush_dcache_mmap_lock, - * within inode_wb_list_lock in __sync_single_inode) + * within bdi.wb->list_lock in __sync_single_inode) * * anon_vma->mutex,mapping->i_mutex (memory_failure, collect_procs_anon) * ->tasklist_lock |