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FROMGIT: mm/pagealloc: sysctl: change watermark_scale_factor max limit to 30%

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For embedded systems with low total memory, having to run applications
with relatively large memory requirements, 10% max limitation for
watermark_scale_factor poses an issue of triggering direct reclaim every
time such application is started.  This results in slow application
startup times and bad end-user experience.

By increasing watermark_scale_factor max limit we allow vendors more
flexibility to choose the right level of kswapd aggressiveness for their
device and workload requirements.

Link: https://lkml.kernel.org/r/20211124193604.2758863-1-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Fengfei Xi <xi.fengfei@h3c.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

(cherry picked from commit 4e36dc369cc7581ac19a7523303e682a53e52e59
 git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master)

Bug: 194652782
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I3e926c8b222933a10c79068d22a1407ff3181824
This commit is contained in:
Suren Baghdasaryan
2021-12-07 17:30:49 +11:00
parent 009596c521
commit 0f047989b0
2 changed files with 3 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/admin-guide/sysctl/vm.rst
View File

@@ -948,7 +948,7 @@ how much memory needs to be free before kswapd goes back to sleep.
The unit is in fractions of 10,000. The default value of 10 means the The unit is in fractions of 10,000. The default value of 10 means the
distances between watermarks are 0.1% of the available memory in the distances between watermarks are 0.1% of the available memory in the
node/system. The maximum value is 1000, or 10% of memory. node/system. The maximum value is 3000, or 30% of memory.
A high rate of threads entering direct reclaim (allocstall) or kswapd A high rate of threads entering direct reclaim (allocstall) or kswapd
going to sleep prematurely (kswapd_low_wmark_hit_quickly) can indicate going to sleep prematurely (kswapd_low_wmark_hit_quickly) can indicate

3
kernel/sysctl.c
View File

@@ -122,6 +122,7 @@ static unsigned long long_max = LONG_MAX;
static int one_hundred = 100; static int one_hundred = 100;
static int two_hundred = 200; static int two_hundred = 200;
static int one_thousand = 1000; static int one_thousand = 1000;
static int three_thousand = 3000;
#ifdef CONFIG_PRINTK #ifdef CONFIG_PRINTK
static int ten_thousand = 10000; static int ten_thousand = 10000;
#endif #endif
@@ -2968,7 +2969,7 @@ static struct ctl_table vm_table[] = {
.mode = 0644, .mode = 0644,
.proc_handler = watermark_scale_factor_sysctl_handler, .proc_handler = watermark_scale_factor_sysctl_handler,
.extra1 = SYSCTL_ONE, .extra1 = SYSCTL_ONE,
.extra2 = &one_thousand, .extra2 = &three_thousand,
}, },
{ {
.procname = "percpu_pagelist_high_fraction", .procname = "percpu_pagelist_high_fraction",