The following commit has been merged into the sched/core branch of tip: Commit-ID: 1abdfe706a579a702799fce465bceb9fb01d407c Gitweb: https://git.kernel.org/tip/1abdfe706a579a702799fce465bceb9fb01d407c Author: Alex Belits <abel...@marvell.com> AuthorDate: Thu, 25 Jun 2020 18:34:41 -04:00 Committer: Peter Zijlstra <pet...@infradead.org> CommitterDate: Wed, 08 Jul 2020 11:39:01 +02:00
lib: Restrict cpumask_local_spread to houskeeping CPUs 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. Signed-off-by: Alex Belits <abel...@marvell.com> Signed-off-by: Nitesh Narayan Lal <nit...@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Link: https://lkml.kernel.org/r/20200625223443.2684-2-nit...@redhat.com --- lib/cpumask.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/lib/cpumask.c b/lib/cpumask.c index fb22fb2..85da6ab 100644 --- 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_MANAGED_IRQ; + 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;
