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authorRohit Seth <rohit.seth@intel.com>2006-01-08 01:00:40 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-08 20:12:40 -0800
commit8ad4b1fb8205340dba16b63467bb23efc27264d6 (patch)
tree9f5c237ead93976e5454c5da5d3bba350a2419c5 /Documentation/sysctl
parent9d0243bca345d5ce25d3f4b74b7facb3a6df1232 (diff)
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[PATCH] Make high and batch sizes of per_cpu_pagelists configurable
As recently there has been lot of traffic on the right values for batch and high water marks for per_cpu_pagelists. This patch makes these two variables configurable through /proc interface. A new tunable /proc/sys/vm/percpu_pagelist_fraction is added. This entry controls the fraction of pages at most in each zone that are allocated for each per cpu page list. The min value for this is 8. It means that we don't allow more than 1/8th of pages in each zone to be allocated in any single per_cpu_pagelist. The batch value of each per cpu pagelist is also updated as a result. It is set to pcp->high/4. The upper limit of batch is (PAGE_SHIFT * 8) Signed-off-by: Rohit Seth <rohit.seth@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'Documentation/sysctl')
-rw-r--r--Documentation/sysctl/vm.txt17
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 89ba1a42a17..6910c0136f8 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -103,3 +103,20 @@ This is used to force the Linux VM to keep a minimum number
of kilobytes free. The VM uses this number to compute a pages_min
value for each lowmem zone in the system. Each lowmem zone gets
a number of reserved free pages based proportionally on its size.
+
+==============================================================
+
+percpu_pagelist_fraction
+
+This is the fraction of pages at most (high mark pcp->high) in each zone that
+are allocated for each per cpu page list. The min value for this is 8. It
+means that we don't allow more than 1/8th of pages in each zone to be
+allocated in any single per_cpu_pagelist. This entry only changes the value
+of hot per cpu pagelists. User can specify a number like 100 to allocate
+1/100th of each zone to each per cpu page list.
+
+The batch value of each per cpu pagelist is also updated as a result. It is
+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.