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[PATCH] drop-pagecache

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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>
This commit is contained in:
Andrew Morton 2006-01-08 01:00:39 -08:00 • committed by Linus Torvalds
parent bec6b0c89b
commit 9d0243bca3
9 changed files with 107 additions and 5 deletions
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7
include/linux/mm.h
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@ -1036,5 +1036,12 @@ int in_gate_area_no_task(unsigned long addr);
/* /proc/<pid>/oom_adj set to -17 protects from the oom-killer */
#define OOM_DISABLE -17
int drop_caches_sysctl_handler(struct ctl_table *, int, struct file *,
void __user *, size_t *, loff_t *);
int shrink_slab(unsigned long scanned, gfp_t gfp_mask,
unsigned long lru_pages);
void drop_pagecache(void);
void drop_slab(void);
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */