Messages in this thread Patch in this message | | | From | Ricardo Neri <> | Subject | [PATCH v4 05/12] sched/fair: Keep a fully_busy SMT sched group as busiest | Date | Thu, 6 Apr 2023 13:31:41 -0700 |
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When comparing two fully_busy scheduling groups, keep the current busiest group if it represents an SMT core. Tasks in such scheduling group share CPU resources and need more help than tasks in a non-SMT fully_busy group.
Cc: Ben Segall <bsegall@google.com> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Ionela Voinescu <ionela.voinescu@arm.com> Cc: Len Brown <len.brown@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tim C. Chen <tim.c.chen@intel.com> Cc: Valentin Schneider <vschneid@redhat.com> Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org Tested-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> --- Changes since v3: * None
Changes since v2: * Introduced this patch.
Changes since v1: * N/A --- kernel/sched/fair.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b151e93ec316..ea23a5163bfa 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9566,10 +9566,22 @@ static bool update_sd_pick_busiest(struct lb_env *env, * contention when accessing shared HW resources. * * XXX for now avg_load is not computed and always 0 so we - * select the 1st one. + * select the 1st one, except if @sg is composed of SMT + * siblings. */ - if (sgs->avg_load <= busiest->avg_load) + + if (sgs->avg_load < busiest->avg_load) return false; + + if (sgs->avg_load == busiest->avg_load) { + /* + * SMT sched groups need more help than non-SMT groups. + * If @sg happens to also be SMT, either choice is good. + */ + if (sds->busiest->flags & SD_SHARE_CPUCAPACITY) + return false; + } + break; case group_has_spare: -- 2.25.1
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