diff options
author | Andrew Morton <akpm@osdl.org> | 2006-01-08 09:00:39 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-01-09 04:12:40 (GMT) |
commit | 9d0243bca345d5ce25d3f4b74b7facb3a6df1232 (patch) | |
tree | a3a0a763bf83a483282dc1c3caab587941a98fc2 /fs | |
parent | bec6b0c89b234090681a4516e20ac5debe3e7c59 (diff) | |
download | linux-9d0243bca345d5ce25d3f4b74b7facb3a6df1232.tar.xz |
[PATCH] drop-pagecache
Add /proc/sys/vm/drop_caches. When written to, this will cause the kernel to
discard as much pagecache and/or reclaimable slab objects as it can. THis
operation requires root permissions.
It won't drop dirty data, so the user should run `sync' first.
Caveats:
a) Holds inode_lock for exorbitant amounts of time.
b) Needs to be taught about NUMA nodes: propagate these all the way through
so the discarding can be controlled on a per-node basis.
This is a debugging feature: useful for getting consistent results between
filesystem benchmarks. We could possibly put it under a config option, but
it's less than 300 bytes.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/Makefile | 2 | ||||
-rw-r--r-- | fs/drop_caches.c | 68 |
2 files changed, 69 insertions, 1 deletions
diff --git a/fs/Makefile b/fs/Makefile index 7367611..35e9aec 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -10,7 +10,7 @@ obj-y := open.o read_write.o file_table.o buffer.o bio.o super.o \ ioctl.o readdir.o select.o fifo.o locks.o dcache.o inode.o \ attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \ seq_file.o xattr.o libfs.o fs-writeback.o mpage.o direct-io.o \ - ioprio.o pnode.o + ioprio.o pnode.o drop_caches.o obj-$(CONFIG_INOTIFY) += inotify.o obj-$(CONFIG_EPOLL) += eventpoll.o diff --git a/fs/drop_caches.c b/fs/drop_caches.c new file mode 100644 index 0000000..4e47623 --- /dev/null +++ b/fs/drop_caches.c @@ -0,0 +1,68 @@ +/* + * Implement the manual drop-all-pagecache function + */ + +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/fs.h> +#include <linux/writeback.h> +#include <linux/sysctl.h> +#include <linux/gfp.h> + +/* A global variable is a bit ugly, but it keeps the code simple */ +int sysctl_drop_caches; + +static void drop_pagecache_sb(struct super_block *sb) +{ + struct inode *inode; + + spin_lock(&inode_lock); + list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { + if (inode->i_state & (I_FREEING|I_WILL_FREE)) + continue; + invalidate_inode_pages(inode->i_mapping); + } + spin_unlock(&inode_lock); +} + +void drop_pagecache(void) +{ + struct super_block *sb; + + spin_lock(&sb_lock); +restart: + list_for_each_entry(sb, &super_blocks, s_list) { + sb->s_count++; + spin_unlock(&sb_lock); + down_read(&sb->s_umount); + if (sb->s_root) + drop_pagecache_sb(sb); + up_read(&sb->s_umount); + spin_lock(&sb_lock); + if (__put_super_and_need_restart(sb)) + goto restart; + } + spin_unlock(&sb_lock); +} + +void drop_slab(void) +{ + int nr_objects; + + do { + nr_objects = shrink_slab(1000, GFP_KERNEL, 1000); + } while (nr_objects > 10); +} + +int drop_caches_sysctl_handler(ctl_table *table, int write, + struct file *file, void __user *buffer, size_t *length, loff_t *ppos) +{ + proc_dointvec_minmax(table, write, file, buffer, length, ppos); + if (write) { + if (sysctl_drop_caches & 1) + drop_pagecache(); + if (sysctl_drop_caches & 2) + drop_slab(); + } + return 0; +} |