From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754677Ab0JNFsj (ORCPT ); Thu, 14 Oct 2010 01:48:39 -0400 Received: from smtp-out.google.com ([74.125.121.35]:47653 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754605Ab0JNFsi (ORCPT ); Thu, 14 Oct 2010 01:48:38 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=A1KgPT3wEHKyh6RUplJtvM/4cKItDgDRZPuVfqmDsd0rBUGBukC7sgxO9W7JSIAdM RlD1YVlp5uHOKCX+ALnMQ== From: Nikhil Rao To: Ingo Molnar , Peter Zijlstra , Mike Galbraith , Suresh Siddha , Venkatesh Pallipadi Cc: linux-kernel@vger.kernel.org, Nikhil Rao Subject: [PATCH 3/4] sched: drop group_capacity to 1 only if local group has extra capacity Date: Wed, 13 Oct 2010 22:48:01 -0700 Message-Id: <1287035281-25579-1-git-send-email-ncrao@google.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1286996978-7007-4-git-send-email-ncrao@google.com> References: <1286996978-7007-4-git-send-email-ncrao@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Resending this patch since the original patch was munged. Thanks to Mike Galbraith for pointing this out. When SD_PREFER_SIBLING is set on a sched domain, drop group_capacity to 1 only if the local group has extra capacity. For niced task balancing, we pull low weight tasks away from a sched group as long as there is capacity in other groups. When all other groups are saturated, we do not drop capacity of the niced group down to 1. This prevents active balance from kicking out the low weight threads and which hurts system utilization. Signed-off-by: Nikhil Rao --- kernel/sched_fair.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 0dd1021..da0c688 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -2030,6 +2030,7 @@ struct sd_lb_stats { unsigned long this_load; unsigned long this_load_per_task; unsigned long this_nr_running; + unsigned long this_group_capacity; /* Statistics of the busiest group */ unsigned long max_load; @@ -2546,15 +2547,18 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu, /* * In case the child domain prefers tasks go to siblings * first, lower the sg capacity to one so that we'll try - * and move all the excess tasks away. + * and move all the excess tasks away. We lower capacity only + * if the local group can handle the extra capacity. */ - if (prefer_sibling) + if (prefer_sibling && !local_group && + sds->this_nr_running < sds->this_group_capacity) sgs.group_capacity = min(sgs.group_capacity, 1UL); if (local_group) { sds->this_load = sgs.avg_load; sds->this = sg; sds->this_nr_running = sgs.sum_nr_running; + sds->this_group_capacity = sgs.group_capacity; sds->this_load_per_task = sgs.sum_weighted_load; } else if (update_sd_pick_busiest(sd, sds, sg, &sgs, this_cpu)) { sds->max_load = sgs.avg_load; -- 1.7.1