Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753728Ab3FELEq (ORCPT ); Wed, 5 Jun 2013 07:04:46 -0400 Received: from merlin.infradead.org ([205.233.59.134]:48769 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751323Ab3FELEp (ORCPT ); Wed, 5 Jun 2013 07:04:45 -0400 Date: Wed, 5 Jun 2013 13:04:34 +0200 From: Peter Zijlstra To: Viresh Kumar Cc: Michael Wang , mingo@redhat.com, linaro-kernel@lists.linaro.org, patches@linaro.org, linux-kernel@vger.kernel.org, robin.randhawa@arm.com, Steve.Bannister@arm.com, Liviu.Dudau@arm.com, charles.garcia-tobin@arm.com, arvind.chauhan@arm.com Subject: Re: [PATCH 1/2] sched: Optimize build_sched_domains() for saving first SD node for a cpu Message-ID: <20130605110434.GY8923@twins.programming.kicks-ass.net> References: <51AEC1C3.1040804@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2402 Lines: 63 On Wed, Jun 05, 2013 at 10:37:29AM +0530, Viresh Kumar wrote: > On 5 June 2013 10:12, Michael Wang wrote: > > Hi, Viresh > > > > On 06/04/2013 07:20 PM, Viresh Kumar wrote: > > [snip] > >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c > >> index 58453b8..638f6cb 100644 > >> --- a/kernel/sched/core.c > >> +++ b/kernel/sched/core.c > >> @@ -6533,16 +6533,13 @@ static int build_sched_domains(const struct cpumask *cpu_map, > >> sd = NULL; > >> for (tl = sched_domain_topology; tl->init; tl++) { > >> sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i); > >> + if (!*per_cpu_ptr(d.sd, i)) > > > > What about: > > if (tl == sched_domain_topology) > > > > It cost less than per_cpu_ptr(), isn't it? > > How can I miss it.. Obviously its better :) > > See if below one looks better (Attached too in case gmail screws up > my mail).. > > --------x-------------x------------------ > > From: Viresh Kumar > Date: Tue, 4 Jun 2013 15:41:15 +0530 > Subject: [PATCH] sched: Optimize build_sched_domains() for saving first SD > node for a cpu > > We are saving first scheduling domain for a cpu in build_sched_domains() by > iterating over the nested sd->child list. We don't actually need to do it this > way. > > tl will be equal to sched_domain_topology for the first iteration and so we can > set *per_cpu_ptr(d.sd, i) based on that. So, save pointer to first SD while > running the iteration loop over tl's. > > Signed-off-by: Viresh Kumar > --- > kernel/sched/core.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 58453b8..08a27be 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -6533,16 +6533,13 @@ static int build_sched_domains(const struct > cpumask *cpu_map, Applying patch patches/viresh_kumar-_patch__sched-optimize_build_sched_domains_for_saving_first_sd.patch patching file kernel/sched/core.c patch: **** malformed patch at line 56: cpumask *cpu_map, -- 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/