From d110235d2c331c4f79e0879f51104be79e17a469 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra <a.p.zijlstra@chello.nl> Date: Wed, 20 Jul 2011 18:42:57 +0200 Subject: [PATCH] sched: Avoid creating superfluous NUMA domains on non-NUMA systems When creating sched_domains, stop when we've covered the entire target span instead of continuing to create domains, only to later find they're redundant and throw them away again. This avoids single node systems from touching funny NUMA sched_domain creation code and reduces the risks of the new SD_OVERLAP code. Requested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Anton Blanchard <anton@samba.org> Cc: mahesh@linux.vnet.ibm.com Cc: benh@kernel.crashing.org Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/1311180177.29152.57.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu> --- kernel/sched.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/sched.c b/kernel/sched.c index 921adf6f6fad..14168c49a154 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -7436,6 +7436,8 @@ static int build_sched_domains(const struct cpumask *cpu_map, sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i); if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) sd->flags |= SD_OVERLAP; + if (cpumask_equal(cpu_map, sched_domain_span(sd))) + break; } while (sd->child) -- GitLab