On Tue, 23 Jun 2020 15:23:29 -0400 Nitesh Narayan Lal <[email protected]> wrote:
> From: Alex Belits <[email protected]> > > The current implementation of cpumask_local_spread() does not respect the > isolated CPUs, i.e., even if a CPU has been isolated for Real-Time task, > it will return it to the caller for pinning of its IRQ threads. Having > these unwanted IRQ threads on an isolated CPU adds up to a latency > overhead. > > Restrict the CPUs that are returned for spreading IRQs only to the > available housekeeping CPUs. > > ... > > --- a/lib/cpumask.c > +++ b/lib/cpumask.c > @@ -6,6 +6,7 @@ > #include <linux/export.h> > #include <linux/memblock.h> > #include <linux/numa.h> > +#include <linux/sched/isolation.h> > > /** > * cpumask_next - get the next cpu in a cpumask > @@ -205,22 +206,27 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask) > */ > unsigned int cpumask_local_spread(unsigned int i, int node) > { > - int cpu; > + int cpu, hk_flags; > + const struct cpumask *mask; > > + hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ; > + mask = housekeeping_cpumask(hk_flags); > /* Wrap: we always want a cpu. */ > - i %= num_online_cpus(); > + i %= cpumask_weight(mask); > > if (node == NUMA_NO_NODE) { > - for_each_cpu(cpu, cpu_online_mask) > + for_each_cpu(cpu, mask) { > if (i-- == 0) > return cpu; > + } > } else { > /* NUMA first. */ > - for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask) > + for_each_cpu_and(cpu, cpumask_of_node(node), mask) { > if (i-- == 0) > return cpu; > + } > > - for_each_cpu(cpu, cpu_online_mask) { > + for_each_cpu(cpu, mask) { > /* Skip NUMA nodes, done above. */ > if (cpumask_test_cpu(cpu, cpumask_of_node(node))) > continue; Are you aware of these changes to cpu_local_spread()? https://lore.kernel.org/lkml/[email protected]/ I don't see a lot of overlap but it would be nice for you folks to check each other's homework ;)
