Messages in this thread | | | Date | Fri, 11 Sep 2020 17:28:54 +0100 | From | Qais Yousef <> | Subject | Re: [RFC PATCH v1 1/1] sched/fair: select idle cpu from idle cpumask in sched domain |
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On 09/10/20 13:42, Aubrey Li wrote: > Added idle cpumask to track idle cpus in sched domain. When a CPU > enters idle, its corresponding bit in the idle cpumask will be set, > and when the CPU exits idle, its bit will be cleared. > > When a task wakes up to select an idle cpu, scanning idle cpumask > has low cost than scanning all the cpus in last level cache domain, > especially when the system is heavily loaded. > > Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com> > --- > include/linux/sched/topology.h | 13 +++++++++++++ > kernel/sched/fair.c | 4 +++- > kernel/sched/topology.c | 2 +- > 3 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h > index fb11091129b3..43a641d26154 100644 > --- a/include/linux/sched/topology.h > +++ b/include/linux/sched/topology.h > @@ -65,8 +65,21 @@ struct sched_domain_shared { > atomic_t ref; > atomic_t nr_busy_cpus; > int has_idle_cores; > + /* > + * Span of all idle CPUs in this domain. > + * > + * NOTE: this field is variable length. (Allocated dynamically > + * by attaching extra space to the end of the structure, > + * depending on how many CPUs the kernel has booted up with) > + */ > + unsigned long idle_cpus_span[];
Can't you use cpumask_var_t and zalloc_cpumask_var() instead?
The patch looks useful. Did it help you with any particular workload? It'd be good to expand on that in the commit message.
Thanks
-- Qais Yousef
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