Messages in this thread | | | Date | Mon, 1 Feb 2021 13:06:03 +0000 | From | Mel Gorman <> | Subject | Re: [PATCH v5 0/4] Scan for an idle sibling in a single pass |
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On Mon, Feb 01, 2021 at 09:13:16AM +0800, Li, Aubrey wrote: > > Peter's series tried to solve three problems at once, this subset addresses > > one problem. > > > > kernel/sched/fair.c | 151 +++++++++++++++++++--------------------- > > kernel/sched/features.h | 1 - > > 2 files changed, 70 insertions(+), 82 deletions(-) > > > > 4 benchmarks measured on a x86 4s system with 24 cores per socket and > 2 HTs per core, total 192 CPUs. > > The load level is [25%, 50%, 75%, 100%]. > > - hackbench almost has a universal win. > - netperf high load has notable changes, as well as tbench 50% load. >
Ok, both netperf and tbench are somewhat expected as at those loads are rapidly idling. Previously I observed that rapidly idling loads can allow the has_idle_cores test pass for short durations and the double scanning means there is a greater chance of finding an idle CPU over the two passes. I think overall it's better to avoid double scanning even if there are counter examples as it's possible we'll get that back through better depth selection in the future.
Thanks.
-- Mel Gorman SUSE Labs
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