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authorPeter Zijlstra <peterz@infradead.org>2020-10-01 16:54:14 +0300
committerPeter Zijlstra <peterz@infradead.org>2020-11-10 20:39:00 +0300
commit14e292f8d45380c519a83d9b0f37089a17eedcdf (patch)
tree50b8a4826a5fa1a806304a497930b46e8282d0ae /lib
parent3015ef4b98f53fe7eba4f5f82f562c0e074d213c (diff)
downloadlinux-14e292f8d45380c519a83d9b0f37089a17eedcdf.tar.xz
sched,rt: Use cpumask_any*_distribute()
Replace a bunch of cpumask_any*() instances with cpumask_any*_distribute(), by injecting this little bit of random in cpu selection, we reduce the chance two competing balance operations working off the same lowest_mask pick the same CPU. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102347.190759694@infradead.org
Diffstat (limited to 'lib')
-rw-r--r--lib/cpumask.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/lib/cpumask.c b/lib/cpumask.c
index 85da6ab4fbb5..35924025097b 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -267,3 +267,21 @@ int cpumask_any_and_distribute(const struct cpumask *src1p,
return next;
}
EXPORT_SYMBOL(cpumask_any_and_distribute);
+
+int cpumask_any_distribute(const struct cpumask *srcp)
+{
+ int next, prev;
+
+ /* NOTE: our first selection will skip 0. */
+ prev = __this_cpu_read(distribute_cpu_mask_prev);
+
+ next = cpumask_next(prev, srcp);
+ if (next >= nr_cpu_ids)
+ next = cpumask_first(srcp);
+
+ if (next < nr_cpu_ids)
+ __this_cpu_write(distribute_cpu_mask_prev, next);
+
+ return next;
+}
+EXPORT_SYMBOL(cpumask_any_distribute);