From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755230Ab2LCNyn (ORCPT ); Mon, 3 Dec 2012 08:54:43 -0500 Received: from mga11.intel.com ([192.55.52.93]:8866 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755154Ab2LCNyj (ORCPT ); Mon, 3 Dec 2012 08:54:39 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,206,1355126400"; d="scan'208";a="258229002" From: Alex Shi To: npiggin@kernel.dk, mingo@redhat.com, peterz@infradead.org Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: [PATCH 02/10] sched: fix find_idlest_group mess logical Date: Mon, 3 Dec 2012 21:54:06 +0800 Message-Id: <1354542848-29638-3-git-send-email-alex.shi@intel.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1354542848-29638-1-git-send-email-alex.shi@intel.com> References: <1354542848-29638-1-git-send-email-alex.shi@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is 4 situations in the function: 1, no task allowed group; so min_load = ULONG_MAX, this_load = 0, idlest = NULL 2, only local group task allowed; so min_load = ULONG_MAX, this_load assigned, idlest = NULL 3, only non-local task group allowed; so min_load assigned, this_load = 0, idlest != NULL 4, local group + another group are task allowed. so min_load assigned, this_load assigned, idlest != NULL Current logical will return NULL in first 3 kinds of scenarios. And still return NULL, if idlest group is heavier then the local group in the 4th situation. Actually, I thought groups in situation 2,3 are also eligible to host the task. And in 4th situation, agree to bias toward local group. So, has this patch. Signed-off-by: Alex Shi --- kernel/sched/fair.c | 12 +++++++++--- 1 files changed, 9 insertions(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index df99456..b40bc2b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2953,6 +2953,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu, int load_idx) { struct sched_group *idlest = NULL, *group = sd->groups; + struct sched_group *this_group = NULL; unsigned long min_load = ULONG_MAX, this_load = 0; int imbalance = 100 + (sd->imbalance_pct-100)/2; @@ -2987,14 +2988,19 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, if (local_group) { this_load = avg_load; - } else if (avg_load < min_load) { + this_group = group; + } + if (avg_load < min_load) { min_load = avg_load; idlest = group; } } while (group = group->next, group != sd->groups); - if (!idlest || 100*this_load < imbalance*min_load) - return NULL; + if (this_group && idlest != this_group) + /* Bias toward our group again */ + if (100*this_load < imbalance*min_load) + idlest = this_group; + return idlest; } -- 1.7.5.4