From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753935AbdK0RaS (ORCPT ); Mon, 27 Nov 2017 12:30:18 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:41922 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752808AbdK0RaR (ORCPT ); Mon, 27 Nov 2017 12:30:17 -0500 From: Morten Rasmussen To: peterz@infradead.org, mingo@redhat.com Cc: dietmar.eggemann@arm.com, vincent.guittot@linaro.org, mgalbraith@suse.de, linux-kernel@vger.kernel.org, Morten Rasmussen Subject: [PATCH] sched/topology: Set SD_PREFER_SIBLING consistently on non-NUMA levels Date: Mon, 27 Nov 2017 17:29:27 +0000 Message-Id: <1511803767-24572-1-git-send-email-morten.rasmussen@arm.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org SD_PREFER_SIBLING adds an additional bias towards spreading tasks on the _parent_ sched_domain even if a sched_group isn't overloaded. It is currently set on: 1. SMT level to promote spreading to sibling cores rather than using sibling HW-threads (caff37ef96eac7fe96a). 2. Non-NUMA levels which don't have the SD_SHARE_PKG_RESOURCES flag set (= DIE level in the default topology) as it was found to improve benchmarks on certain NUMA systems (6956dc568f34107f1d02b). 3. Any non-NUMA level that inherits the flag due to elimination of its parent sched_domain level in the de-generate step of the sched_domain hierarchy set up (= MC level in the default topology). Preferring siblings seems to be a useful tweak for all non-NUMA levels, so we should enable it on all non-NUMA levels. As it is, it is possible to have it SMT and DIE, but not MC in between when using the default topology. Signed-off-by: Morten Rasmussen cc: Ingo Molnar cc: Peter Zijlstra --- kernel/sched/topology.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 6798276d29af..7f70806bfa0f 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1122,7 +1122,7 @@ sd_init(struct sched_domain_topology_level *tl, | 0*SD_SHARE_CPUCAPACITY | 0*SD_SHARE_PKG_RESOURCES | 0*SD_SERIALIZE - | 0*SD_PREFER_SIBLING + | 1*SD_PREFER_SIBLING | 0*SD_NUMA | sd_flags , @@ -1153,7 +1153,6 @@ sd_init(struct sched_domain_topology_level *tl, } if (sd->flags & SD_SHARE_CPUCAPACITY) { - sd->flags |= SD_PREFER_SIBLING; sd->imbalance_pct = 110; sd->smt_gain = 1178; /* ~15% */ @@ -1168,6 +1167,7 @@ sd_init(struct sched_domain_topology_level *tl, sd->busy_idx = 3; sd->idle_idx = 2; + sd->flags &= ~SD_PREFER_SIBLING; sd->flags |= SD_SERIALIZE; if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) { sd->flags &= ~(SD_BALANCE_EXEC | @@ -1177,7 +1177,6 @@ sd_init(struct sched_domain_topology_level *tl, #endif } else { - sd->flags |= SD_PREFER_SIBLING; sd->cache_nice_tries = 1; sd->busy_idx = 2; sd->idle_idx = 1; -- 2.7.4