On Thu, Jul 02, 2020 at 11:27:52AM +0200, Dietmar Eggemann wrote: > On 17/06/2020 16:52, Peter Puhov wrote: > > On Wed, 17 Jun 2020 at 06:50, Valentin Schneider > > <[email protected]> wrote: > >> > >> > >> On 16/06/20 17:48, [email protected] wrote: > >>> From: Peter Puhov <[email protected]> > >>> We tested this patch with following benchmarks: > >>> perf bench -f simple sched pipe -l 4000000 > >>> perf bench -f simple sched messaging -l 30000 > >>> perf bench -f simple mem memset -s 3GB -l 15 -f default > >>> perf bench -f simple futex wake -s -t 640 -w 1 > >>> sysbench cpu --threads=8 --cpu-max-prime=10000 run > >>> sysbench memory --memory-access-mode=rnd --threads=8 run > >>> sysbench threads --threads=8 run > >>> sysbench mutex --mutex-num=1 --threads=8 run > >>> hackbench --loops 20000 > >>> hackbench --pipe --threads --loops 20000 > >>> hackbench --pipe --threads --loops 20000 --datasize 4096 > >>> > >>> and found some performance improvements in: > >>> sysbench threads > >>> sysbench mutex > >>> perf bench futex wake > >>> and no regressions in others. > >>> > >> > >> One nitpick for the results of those: condensing them in a table form would > >> make them more reader-friendly. Perhaps something like: > >> > >> | Benchmark | Metric | Lower is better? | BASELINE | SERIES | > >> DELTA | > >> |------------------+----------+------------------+----------+--------+-------| > >> | Sysbench threads | # events | No | 45526 | 56567 | > >> +24% | > >> | Sysbench mutex | ... | | | | > >> | > >> > >> If you want to include more stats for each benchmark, you could have one > >> table > >> per (e.g. see [1]) - it'd still be a more readable form (or so I believe). > > Wouldn't Unix Bench's 'execl' and 'spawn' be the ultimate test cases > for those kind of changes? > > I only see minor improvements with tip/sched/core as base on hikey620 > (Arm64 octa-core). > > base w/ patch > ./Run spawn -c 8 -i 10 633.6 635.1 > > ./Run execl -c 8 -i 10 1187.5 1190.7 > > > At the end of find_idlest_group(), when comparing local and idlest, it > is explicitly mentioned that number of idle_cpus is used instead of > utilization. > The comparision between potential idle groups and local & idlest group > should probably follow the same rules. >
There is the secondary hazard that what update_sd_pick_busiest returns is checked later by find_busiest_group when considering the imbalance between NUMA nodes. This particular patch splits basic communicating tasks cross-node again at fork time so cross node communication is reintroduced (same applies if sum_nr_running is used instead of group_util). -- Mel Gorman SUSE Labs
