Messages in this thread | | | Subject | Re: [PATCH v4 0/5] remove runnable_load_avg and improve group_classify | From | Parth Shah <> | Date | Sun, 23 Feb 2020 11:38:23 +0530 |
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Hi,
On 2/21/20 6:57 PM, Vincent Guittot wrote: > This new version stays quite close to the previous one and should > replace without problems the previous one that part of Mel's patchset: > https://lkml.org/lkml/2020/2/14/156 > > NUMA load balancing is the last remaining piece of code that uses the > runnable_load_avg of PELT to balance tasks between nodes. The normal > load_balance has replaced it by a better description of the current state > of the group of cpus. The same policy can be applied to the numa > balancing. > > Once unused, runnable_load_avg can be replaced by a simpler runnable_avg > signal that tracks the waiting time of tasks on rq. Currently, the state > of a group of CPUs is defined thanks to the number of running task and the > level of utilization of rq. But the utilization can be temporarly low > after the migration of a task whereas the rq is still overloaded with > tasks. In such case where tasks were competing for the rq, the > runnable_avg will stay high after the migration. > > Some hackbench results: > > - small arm64 dual quad cores system > hackbench -l (2560/#grp) -g #grp > > grp tip/sched/core +patchset improvement > 1 1,327(+/-10,06 %) 1,247(+/-5,45 %) 5,97 % > 4 1,250(+/- 2,55 %) 1,207(+/-2,12 %) 3,42 % > 8 1,189(+/- 1,47 %) 1,179(+/-1,93 %) 0,90 % > 16 1,221(+/- 3,25 %) 1,219(+/-2,44 %) 0,16 % > > - large arm64 2 nodes / 224 cores system > hackbench -l (256000/#grp) -g #grp > > grp tip/sched/core +patchset improvement > 1 14,197(+/- 2,73 %) 13,917(+/- 2,19 %) 1,98 % > 4 6,817(+/- 1,27 %) 6,523(+/-11,96 %) 4,31 % > 16 2,930(+/- 1,07 %) 2,911(+/- 1,08 %) 0,66 % > 32 2,735(+/- 1,71 %) 2,725(+/- 1,53 %) 0,37 % > 64 2,702(+/- 0,32 %) 2,717(+/- 1,07 %) -0,53 % > 128 3,533(+/-14,66 %) 3,123(+/-12,47 %) 11,59 % > 256 3,918(+/-19,93 %) 3,390(+/- 5,93 %) 13,47 %
[...]
I performed similar experiment on IBM POWER9 system with 2 nodes 44 cores system (22 per node)
- hackbench -l (256000/#grp) -g #grp +-----+----------------+-------+ | grp | tip/sched/core | v4 | +-----+----------------+-------+ | 1 | 76.97 | 76.31 | | 4 | 56.56 | 56.86 | | 8 | 54.23 | 54.25 | | 16 | 53.94 | 53.24 | | 32 | 54.10 | 54.01 | | 64 | 54.38 | 54.35 | | 128 | 55.11 | 55.08 | | 256 | 55.97 | 56.04 | | 512 | 54.81 | 55.5 | +-----+----------------+-------+ - deviation in the result is very marginal ( < 1%)
The results shows no changes with respect to the hackbench. I will do further benchmarking to see if any observable changes occurs.
- Parth
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