From b31dc66a54ad986b6b73bdc49c8efc17cbad1833 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 13 Jun 2006 08:26:10 +0200 Subject: [PATCH] Kill PF_SYNCWRITE flag A process flag to indicate whether we are doing sync io is incredibly ugly. It also causes performance problems when one does a lot of async io and then proceeds to sync it. Part of the io will go out as async, and the other part as sync. This causes a disconnect between the previously submitted io and the synced io. For io schedulers such as CFQ, this will cause us lost merges and suboptimal behaviour in scheduling. Remove PF_SYNCWRITE completely from the fsync/msync paths, and let the O_DIRECT path just directly indicate that the writes are sync by using WRITE_SYNC instead. Signed-off-by: Jens Axboe diff --git a/block/as-iosched.c b/block/as-iosched.c index 9b13d72..56c99fa 100644 --- a/block/as-iosched.c +++ b/block/as-iosched.c @@ -1339,7 +1339,7 @@ static void as_add_request(request_queue_t *q, struct request *rq) arq->state = AS_RQ_NEW; if (rq_data_dir(arq->request) == READ - || current->flags&PF_SYNCWRITE) + || (arq->request->flags & REQ_RW_SYNC)) arq->is_sync = 1; else arq->is_sync = 0; diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index c88f161d..4c4e9cc 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -277,8 +277,6 @@ static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsi static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *); static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask); -#define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE) - /* * lots of deadline iosched dupes, can be abstracted later... */ @@ -334,7 +332,7 @@ static int cfq_queue_empty(request_queue_t *q) static inline pid_t cfq_queue_pid(struct task_struct *task, int rw) { - if (rw == READ || process_sync(task)) + if (rw == READ || rw == WRITE_SYNC) return task->pid; return CFQ_KEY_ASYNC; diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index 17c42dd..2270bb4 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -2827,6 +2827,9 @@ static void init_request_from_bio(struct request *req, struct bio *bio) if (unlikely(bio_barrier(bio))) req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE); + if (bio_sync(bio)) + req->flags |= REQ_RW_SYNC; + req->errors = 0; req->hard_sector = req->sector = bio->bi_sector; req->hard_nr_sectors = req->nr_sectors = bio_sectors(bio); diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c index 6f88747..a43dc90 100644 --- a/drivers/usb/gadget/file_storage.c +++ b/drivers/usb/gadget/file_storage.c @@ -1906,7 +1906,6 @@ static int fsync_sub(struct lun *curlun) inode = filp->f_dentry->d_inode; mutex_lock(&inode->i_mutex); - current->flags |= PF_SYNCWRITE; rc = filemap_fdatawrite(inode->i_mapping); err = filp->f_op->fsync(filp, filp->f_dentry, 1); if (!rc) @@ -1914,7 +1913,6 @@ static int fsync_sub(struct lun *curlun) err = filemap_fdatawait(inode->i_mapping); if (!rc) rc = err; - current->flags &= ~PF_SYNCWRITE; mutex_unlock(&inode->i_mutex); VLDBG(curlun, "fdatasync -> %d\n", rc); return rc; diff --git a/fs/buffer.c b/fs/buffer.c index 23f1f3a..373bb62 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -331,7 +331,6 @@ long do_fsync(struct file *file, int datasync) goto out; } - current->flags |= PF_SYNCWRITE; ret = filemap_fdatawrite(mapping); /* @@ -346,7 +345,6 @@ long do_fsync(struct file *file, int datasync) err = filemap_fdatawait(mapping); if (!ret) ret = err; - current->flags &= ~PF_SYNCWRITE; out: return ret; } diff --git a/fs/direct-io.c b/fs/direct-io.c index b05d1b2..538fb04 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -162,7 +162,7 @@ static int dio_refill_pages(struct dio *dio) NULL); /* vmas */ up_read(¤t->mm->mmap_sem); - if (ret < 0 && dio->blocks_available && (dio->rw == WRITE)) { + if (ret < 0 && dio->blocks_available && (dio->rw & WRITE)) { struct page *page = ZERO_PAGE(dio->curr_user_address); /* * A memory fault, but the filesystem has some outstanding @@ -535,7 +535,7 @@ static int get_more_blocks(struct dio *dio) map_bh->b_state = 0; map_bh->b_size = fs_count << dio->inode->i_blkbits; - create = dio->rw == WRITE; + create = dio->rw & WRITE; if (dio->lock_type == DIO_LOCKING) { if (dio->block_in_file < (i_size_read(dio->inode) >> dio->blkbits)) @@ -867,7 +867,7 @@ do_holes: loff_t i_size_aligned; /* AKPM: eargh, -ENOTBLK is a hack */ - if (dio->rw == WRITE) { + if (dio->rw & WRITE) { page_cache_release(page); return -ENOTBLK; } @@ -1045,7 +1045,7 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, } } /* end iovec loop */ - if (ret == -ENOTBLK && rw == WRITE) { + if (ret == -ENOTBLK && (rw & WRITE)) { /* * The remaining part of the request will be * be handled by buffered I/O when we return @@ -1089,7 +1089,7 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, if (dio->is_async) { int should_wait = 0; - if (dio->result < dio->size && rw == WRITE) { + if (dio->result < dio->size && (rw & WRITE)) { dio->waiter = current; should_wait = 1; } @@ -1142,7 +1142,7 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, ret = transferred; /* We could have also come here on an AIO file extend */ - if (!is_sync_kiocb(iocb) && rw == WRITE && + if (!is_sync_kiocb(iocb) && (rw & WRITE) && ret >= 0 && dio->result == dio->size) /* * For AIO writes where we have completed the @@ -1194,7 +1194,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, int acquire_i_mutex = 0; if (rw & WRITE) - current->flags |= PF_SYNCWRITE; + rw = WRITE_SYNC; if (bdev) bdev_blkbits = blksize_bits(bdev_hardsect_size(bdev)); @@ -1270,7 +1270,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, * even for AIO, we need to wait for i/o to complete before * returning in this case. */ - dio->is_async = !is_sync_kiocb(iocb) && !((rw == WRITE) && + dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) && (end > i_size_read(inode))); retval = direct_io_worker(rw, iocb, inode, iov, offset, @@ -1284,8 +1284,6 @@ out: mutex_unlock(&inode->i_mutex); else if (acquire_i_mutex) mutex_lock(&inode->i_mutex); - if (rw & WRITE) - current->flags &= ~PF_SYNCWRITE; return retval; } EXPORT_SYMBOL(__blockdev_direct_IO); diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 6db95cf..031b27a 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -623,7 +623,6 @@ int generic_osync_inode(struct inode *inode, struct address_space *mapping, int int need_write_inode_now = 0; int err2; - current->flags |= PF_SYNCWRITE; if (what & OSYNC_DATA) err = filemap_fdatawrite(mapping); if (what & (OSYNC_METADATA|OSYNC_DATA)) { @@ -636,7 +635,6 @@ int generic_osync_inode(struct inode *inode, struct address_space *mapping, int if (!err) err = err2; } - current->flags &= ~PF_SYNCWRITE; spin_lock(&inode_lock); if ((inode->i_state & I_DIRTY) && diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 3457e7b..482a21d 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -241,6 +241,7 @@ enum rq_flag_bits { __REQ_PM_RESUME, /* resume request */ __REQ_PM_SHUTDOWN, /* shutdown request */ __REQ_ORDERED_COLOR, /* is before or after barrier */ + __REQ_RW_SYNC, /* request is sync (O_DIRECT) */ __REQ_NR_BITS, /* stops here */ }; @@ -270,6 +271,7 @@ enum rq_flag_bits { #define REQ_PM_RESUME (1 << __REQ_PM_RESUME) #define REQ_PM_SHUTDOWN (1 << __REQ_PM_SHUTDOWN) #define REQ_ORDERED_COLOR (1 << __REQ_ORDERED_COLOR) +#define REQ_RW_SYNC (1 << __REQ_RW_SYNC) /* * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME diff --git a/include/linux/sched.h b/include/linux/sched.h index a9d23c7..38b4791e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -941,12 +941,11 @@ static inline void put_task_struct(struct task_struct *t) #define PF_KSWAPD 0x00040000 /* I am kswapd */ #define PF_SWAPOFF 0x00080000 /* I am in swapoff */ #define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */ -#define PF_SYNCWRITE 0x00200000 /* I am doing a sync write */ -#define PF_BORROWED_MM 0x00400000 /* I am a kthread doing use_mm */ -#define PF_RANDOMIZE 0x00800000 /* randomize virtual address space */ -#define PF_SWAPWRITE 0x01000000 /* Allowed to write to swap */ -#define PF_SPREAD_PAGE 0x04000000 /* Spread page cache over cpuset */ -#define PF_SPREAD_SLAB 0x08000000 /* Spread some slab caches over cpuset */ +#define PF_BORROWED_MM 0x00200000 /* I am a kthread doing use_mm */ +#define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */ +#define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */ +#define PF_SPREAD_PAGE 0x01000000 /* Spread page cache over cpuset */ +#define PF_SPREAD_SLAB 0x02000000 /* Spread some slab caches over cpuset */ #define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */ /* diff --git a/mm/msync.c b/mm/msync.c index bc6c953..d083544 100644 --- a/mm/msync.c +++ b/mm/msync.c @@ -170,8 +170,6 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags) * just ignore them, but return -ENOMEM at the end. */ down_read(¤t->mm->mmap_sem); - if (flags & MS_SYNC) - current->flags |= PF_SYNCWRITE; vma = find_vma(current->mm, start); if (!vma) { error = -ENOMEM; @@ -228,7 +226,6 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags) } } while (vma && !done); out_unlock: - current->flags &= ~PF_SYNCWRITE; up_read(¤t->mm->mmap_sem); out: return error; -- cgit v0.10.2