Messages in this thread | | | Date | Wed, 10 Apr 2024 06:27:04 -0700 | From | Yury Norov <> | Subject | Re: [PATCH 0/2 RESEND] sched/topology: Optimize topology_span_sane() |
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On Tue, Apr 09, 2024 at 10:52:48AM -0500, Kyle Meyer wrote: > A soft lockup is being detected in build_sched_domains() on 32 socket > Sapphire Rapids systems with 3840 processors. > > topology_span_sane(), called by build_sched_domains(), checks that each > processor's non-NUMA scheduling domains are completely equal or > completely disjoint. If a non-NUMA scheduling domain partially overlaps > another, scheduling groups can break. > > This series adds for_each_cpu_from() as a generic cpumask macro to > optimize topology_span_sane() by removing duplicate comparisons. The > total number of comparisons is reduced from N * (N - 1) to > N * (N - 1) / 2 (per non-NUMA scheduling domain level), decreasing the > boot time by approximately 20 seconds and preventing the soft lockup on > the mentioned systems. > > RESEND because Valentin Schneider reported that PATCH 2/2 wasn't > delivered to all recipients.
Hmm... And this one doesn't have #1, at least for me. Can you please resend again, so we all will have the series as a whole?
Also, can you rephrase this from patch #1 because it confuses people:
> + * for_each_cpu_from - iterate over every cpu present in @mask, starting at @cpu
Maybe: iterate over CPUs present in a @mask greater than a @cpu? Or similar.
Thanks, Yury
> Kyle Meyer (2): > cpumask: Add for_each_cpu_from() > sched/topology: Optimize topology_span_sane() > > include/linux/cpumask.h | 10 ++++++++++ > kernel/sched/topology.c | 6 ++---- > 2 files changed, 12 insertions(+), 4 deletions(-) > > -- > 2.44.0
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