Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755319AbZCFGbh (ORCPT ); Fri, 6 Mar 2009 01:31:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754207AbZCFG3c (ORCPT ); Fri, 6 Mar 2009 01:29:32 -0500 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:49873 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753932AbZCFG3b (ORCPT ); Fri, 6 Mar 2009 01:29:31 -0500 From: Gautham R Shenoy Subject: [PATCH V3 6/6] sched: Fix sd_parent_degenerate for SD_POWERSAVINGS_BALANCE. To: "Vaidyanathan Srinivasan" , "Balbir Singh" , "Peter Zijlstra" , "Ingo Molnar" , "Suresh Siddha" Cc: "Dipankar Sarma" , efault@gmx.de, andi@firstfloor.org, linux-kernel@vger.kernel.org, Gautham R Shenoy , Vaidyanathan Srinivasan Date: Fri, 06 Mar 2009 11:59:21 +0530 Message-ID: <20090306062921.9445.60671.stgit@sofia.in.ibm.com> In-Reply-To: <20090306060513.9445.28732.stgit@sofia.in.ibm.com> References: <20090306060513.9445.28732.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 35e1651..d27b8e3 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/