From 9d0243bca345d5ce25d3f4b74b7facb3a6df1232 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Sun, 8 Jan 2006 01:00:39 -0800 Subject: [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 Signed-off-by: Linus Torvalds --- include/linux/mm.h | 7 +++++++ include/linux/sysctl.h | 1 + 2 files changed, 8 insertions(+) (limited to 'include') diff --git a/include/linux/mm.h b/include/linux/mm.h index bc01fff3aa01..83c651f25188 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1036,5 +1036,12 @@ int in_gate_area_no_task(unsigned long addr); /* /proc//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 */ diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index a9b80fc7f0f3..4cd267fe87ec 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -180,6 +180,7 @@ enum VM_VFS_CACHE_PRESSURE=26, /* dcache/icache reclaim pressure */ VM_LEGACY_VA_LAYOUT=27, /* legacy/compatibility virtual address space layout */ VM_SWAP_TOKEN_TIMEOUT=28, /* default time for token time out */ + VM_DROP_PAGECACHE=29, /* int: nuke lots of pagecache */ }; -- cgit 1.4.1