Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> writes: > On Thu, Oct 12, 2023 at 03:48:04PM +0800, Huang, Ying wrote: >> " >> On a 2-socket Intel server with 224 logical CPU, we run 8 kbuild >> instances in parallel (each with `make -j 28`) in 8 cgroup. This >> simulates the kbuild server that is used by 0-Day kbuild service. >> With the patch, The number of pages allocated from zone (instead of >> from PCP) decreases 21.4%. >> " >> >> I also showed the performance number for each step of optimization as >> follows (copied from the above patchset V2 link). >> >> " >> build time lock contend% free_high alloc_zone >> ---------- ---------- --------- ---------- >> base 100.0 13.5 100.0 100.0 >> patch1 99.2 10.6 19.2 95.6 >> patch3 99.2 11.7 7.1 95.6 >> patch5 98.4 10.0 8.2 97.1 >> patch7 94.9 0.7 3.0 19.0 >> patch9 94.9 0.6 2.7 15.0 <-- this patch >> patch10 94.9 0.9 8.8 18.6 >> " >> >> Although I think the patch is helpful via avoiding the unnecessary >> pcp->high decaying, thus reducing the zone lock contention. There's no >> visible benchmark score change for the patch. >> > > Thanks! > > Given that it's another PCP field with an update in a relatively hot > path, I would suggest dropping this patch entirely if it does not affect > performance. It has the risk of being a magical heuristic that we forget > later whether it's even worthwhile. OK. Hope we can find some workloads that can benefit from the patch in the future. -- Best Regards, Huang, Ying
