Commit 1743660b authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds

[PATCH] Zone reclaim: proc override

proc support for zone reclaim

This patch creates a proc entry /proc/sys/vm/zone_reclaim_mode that may be
used to override the automatic determination of the zone reclaim made on
Signed-off-by: default avatarChristoph Lameter <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 9eeff239
......@@ -27,6 +27,7 @@ Currently, these files are in /proc/sys/vm:
- laptop_mode
- block_dump
- drop-caches
- zone_reclaim_mode
......@@ -120,3 +121,20 @@ set to pcp->high/4. The upper limit of batch is (PAGE_SHIFT * 8)
The initial value is zero. Kernel does not use this value at boot time to set
the high water marks for each per cpu page list.
This is set during bootup to 1 if it is determined that pages from
remote zones will cause a significant performance reduction. The
page allocator will then reclaim easily reusable pages (those page
cache pages that are currently not used) before going off node.
The user can override this setting. It may be beneficial to switch
off zone reclaim if the system is used for a file server and all
of memory should be used for caching files from disk.
It may be beneficial to switch this on if one wants to do zone
reclaim regardless of the numa distances in the system.
......@@ -182,6 +182,7 @@ enum
VM_SWAP_TOKEN_TIMEOUT=28, /* default time for token time out */
VM_DROP_PAGECACHE=29, /* int: nuke lots of pagecache */
VM_PERCPU_PAGELIST_FRACTION=30,/* int: fraction of pages in each percpu_pagelist */
VM_ZONE_RECLAIM_MODE=31,/* reclaim local zone memory before going off node */
......@@ -869,6 +869,17 @@ static ctl_table vm_table[] = {
.proc_handler = &proc_dointvec_jiffies,
.strategy = &sysctl_jiffies,
.procname = "zone_reclaim_mode",
.data = &zone_reclaim_mode,
.maxlen = sizeof(zone_reclaim_mode),
.mode = 0644,
.proc_handler = &proc_dointvec,
.strategy = &zero,
{ .ctl_name = 0 }
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