summary refs log tree commit diff
path: root/samples/configfs
diff options
context:
space:
mode:
authorVitaly Wool <vitaly.wool@konsulko.com>2020-01-30 22:15:04 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-31 10:30:39 -0800
commit45190f01dd402112d3d22c0ddc4152994f9e1e55 (patch)
treed707c75e478a464d43095393197140a587b88c99 /samples/configfs
parent3d680bdf60a5bade3e8cbd049927e7f8b1d3fe97 (diff)
downloadlinux-45190f01dd402112d3d22c0ddc4152994f9e1e55.tar.gz
mm/zswap.c: add allocation hysteresis if pool limit is hit
zswap will always try to shrink pool when zswap is full.  If there is a
high pressure on zswap it will result in flipping pages in and out zswap
pool without any real benefit, and the overall system performance will
drop.  The previous discussion on this subject [1] ended up with a
suggestion to implement a sort of hysteresis to refuse taking pages into
zswap pool until it has sufficient space if the limit has been hit.
This is my take on this.

Hysteresis is controlled with a sysfs-configurable parameter (namely,
/sys/kernel/debug/zswap/accept_threhsold_percent).  It specifies the
threshold at which zswap would start accepting pages again after it
became full.  Setting this parameter to 100 disables the hysteresis and
sets the zswap behavior to pre-hysteresis state.

[1] https://lkml.org/lkml/2019/11/8/949

Link: http://lkml.kernel.org/r/20200108200118.15563-1-vitaly.wool@konsulko.com
Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'samples/configfs')
0 files changed, 0 insertions, 0 deletions