mm/page_alloc: introduce vm.percpu_pagelist_high_fraction -fix

Vlastimil Babka pointed out that the documentation for
vm.percpu_pagelist_high_fraction is potentially misleading so fix it.

This is a fix to the mmotm patch
mm-page_alloc-introduce-vmpercpu_pagelist_high_fraction.patch

Link: https://lkml.kernel.org/r/20210528151010.GQ30378@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst
index e85c2f21d209a36b84f96aef4248c787a0447adf..2da25735a6291e208a1f73dbfd7e2dcf6f8e9fa5 100644 (file)
--- a/Documentation/admin-guide/sysctl/vm.rst
+++ b/Documentation/admin-guide/sysctl/vm.rst
@@ -793,15 +793,16 @@ why oom happens. You can get snapshot.
 percpu_pagelist_high_fraction
 =============================
 
-This is the fraction of pages in each zone that are allocated for each
-per cpu page list.  The min value for this is 8.  It means that we do
-not 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 remains the same regardless of the
-value of the high fraction so allocation latencies are unaffected.
+This is the fraction of pages in each zone that are can be stored to
+per-cpu page lists. It is an upper boundary that is divided depending
+on the number of online CPUs. The min value for this is 8 which means
+that we do not allow more than 1/8th of pages in each zone to be stored
+on per-cpu page lists. This entry only changes the value of hot per-cpu
+page lists. A user can specify a number like 100 to allocate 1/100th of
+each zone between per-cpu lists.
+
+The batch value of each per-cpu page list remains the same regardless of
+the value of the high fraction so allocation latencies are unaffected.
 
 The initial value is zero. Kernel uses this value to set the high pcp->high
 mark based on the low watermark for the zone and the number of local