On Wed, Aug 31, 2022 at 3:02 AM Mel Gorman <mgorman@xxxxxxx> wrote: > > On Tue, Aug 30, 2022 at 02:48:52PM -0700, Suren Baghdasaryan wrote: > > From: Kent Overstreet <kent.overstreet@xxxxxxxxx> > > > > This patch adds lib/lazy-percpu-counter.c, which implements counters > > that start out as atomics, but lazily switch to percpu mode if the > > update rate crosses some threshold (arbitrarily set at 256 per second). > > > > Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx> > > Why not use percpu_counter? It has a per-cpu counter that is synchronised > when a batch threshold (default 32) is exceeded and can explicitly sync > the counters when required assuming the synchronised count is only needed > when reading debugfs. The intent is to use atomic counters for places that are not updated very often. This would save memory required for the counters. Originally I had a config option to choose which counter type to use but with lazy counters we sacrifice memory for performance only when needed while keeping the other counters small. > > -- > Mel Gorman > SUSE Labs
