From 98c9389042f4d1e6aa73fbaf79e2e962c9497fc5 Mon Sep 17 00:00:00 2001 From: Michal Clapinski Date: Fri, 4 Apr 2025 13:11:03 +0200 Subject: mm/compaction: reduce the difference between low and high watermarks Reduce the diff between low and high watermarks when compaction proactiveness is set to high. This allows users who set the proactiveness really high to have more stable fragmentation score over time. Link: https://lkml.kernel.org/r/20250404111103.1994507-3-mclapinski@google.com Signed-off-by: Michal Clapinski Cc: Mel Gorman Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- Documentation/admin-guide/sysctl/vm.rst | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation/admin-guide/sysctl') diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst index 8290177b4f75..b325bfbc2611 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -131,6 +131,12 @@ to latency spikes in unsuspecting applications. The kernel employs various heuristics to avoid wasting CPU cycles if it detects that proactive compaction is not being effective. +Setting the value above 80 will, in addition to lowering the acceptable level +of fragmentation, make the compaction code more sensitive to increases in +fragmentation, i.e. compaction will trigger more often, but reduce +fragmentation by a smaller amount. +This makes the fragmentation level more stable over time. + Be careful when setting it to extreme values like 100, as that may cause excessive background compaction activity. -- cgit v1.2.3