Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757566AbZCRJYf (ORCPT ); Wed, 18 Mar 2009 05:24:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757258AbZCRJWz (ORCPT ); Wed, 18 Mar 2009 05:22:55 -0400 Received: from e28smtp09.in.ibm.com ([59.145.155.9]:37734 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755213AbZCRJWx (ORCPT ); Wed, 18 Mar 2009 05:22:53 -0400 From: Gautham R Shenoy Subject: [PATCH 3 6/6] sched: Fix sd_parent_degenerate for SD_POWERSAVINGS_BALANCE. To: "Vaidyanathan Srinivasan" , "Peter Zijlstra" , "Ingo Molnar" Cc: linux-kernel@vger.kernel.org, "Suresh Siddha" , "Balbir Singh" , Gautham R Shenoy , Vaidyanathan Srinivasan Date: Wed, 18 Mar 2009 14:52:48 +0530 Message-ID: <20090318092248.24787.38811.stgit@sofia.in.ibm.com> In-Reply-To: <20090318092054.24787.18730.stgit@sofia.in.ibm.com> References: <20090318092054.24787.18730.stgit@sofia.in.ibm.com> User-Agent: StGIT/0.14.2 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1811 Lines: 49 Currently a sched_domain having a single group can be prevented from getting degenerated if it contains a SD_POWERSAVINGS_BALANCE flag. But since it has only one group, it won't have any scope for performing powersavings balance as it does not have a sibling group to pull from. Apart from not provide any powersavings, it also fails to participate in normal load-balancing. Fix this by allowing such a sched_domain to degenerate and pass on the responsibility of performing the POWERSAVINGS_BALANCE to it's parent domain. Signed-off-by: Gautham R Shenoy Cc: Vaidyanathan Srinivasan --- kernel/sched.c | 14 ++++++++++++++ 1 files changed, 14 insertions(+), 0 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 651550c..0e7882a 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6970,6 +6970,20 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) SD_SHARE_PKG_RESOURCES); if (nr_node_ids == 1) pflags &= ~SD_SERIALIZE; + + /* + * If the only flag that is preventing us from degenerating + * a domain with a single group is SD_POWERSAVINGS_BALANCE + * check if it can be transferred to the new parent, + * and degenerate this domain. With a single + * group, it anyway can't contribute to power-aware load + * balancing. + */ + if (pflags & SD_POWERSAVINGS_BALANCE && parent->parent) { + pflags &= ~SD_POWERSAVINGS_BALANCE; + parent->parent->flags |= + sd_power_saving_flags(parent->level); + } } if (~cflags & pflags) return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/