Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756860AbYLKSzp (ORCPT ); Thu, 11 Dec 2008 13:55:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755762AbYLKSzg (ORCPT ); Thu, 11 Dec 2008 13:55:36 -0500 Received: from E23SMTP03.au.ibm.com ([202.81.18.172]:38713 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755649AbYLKSzf (ORCPT ); Thu, 11 Dec 2008 13:55:35 -0500 Date: Fri, 12 Dec 2008 00:25:29 +0530 From: Balbir Singh To: Vaidyanathan Srinivasan Cc: Linux Kernel , Suresh B Siddha , Venkatesh Pallipadi , Peter Zijlstra , Ingo Molnar , Dipankar Sarma , Vatsa , Gautham R Shenoy , Andi Kleen , David Collier-Brown , Tim Connors , Max Krasnyansky , Gregory Haskins Subject: Re: [RFC PATCH v5 1/7] sched: Framework for sched_mc/smt_power_savings=N Message-ID: <20081211185528.GN3008@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com Mail-Followup-To: Vaidyanathan Srinivasan , Linux Kernel , Suresh B Siddha , Venkatesh Pallipadi , Peter Zijlstra , Ingo Molnar , Dipankar Sarma , Vatsa , Gautham R Shenoy , Andi Kleen , David Collier-Brown , Tim Connors , Max Krasnyansky , Gregory Haskins References: <20081211173831.2020.57550.stgit@drishya.in.ibm.com> <20081211174237.2020.77181.stgit@drishya.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20081211174237.2020.77181.stgit@drishya.in.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3641 Lines: 107 * Vaidyanathan Srinivasan [2008-12-11 23:12:37]: > From: Gautham R Shenoy > > *** RFC patch of work in progress and not for inclusion. *** > > Currently the sched_mc/smt_power_savings variable is a boolean, which either > enables or disables topology based power savings. This extends the behaviour of > the variable from boolean to multivalued, such that based on the value, we > decide how aggressively do we want to perform topology based powersavings > balance. > > Variable levels of power saving tunable would benefit end user to match the > required level of power savings vs performance trade off depending on the > system configuration and workloads. > > This initial version makes the sched_mc_power_savings global variable to take > more values (0,1,2). > > Later version is expected to add new member sd->powersavings_level at the multi > core CPU level sched_domain. This make all sd->flags check for > SD_POWERSAVINGS_BALANCE into a different macro that will check for > powersavings_level. > > The power savings level setting should be in one place either in the > sched_mc_power_savings global variable or contained within the appropriate > sched_domain structure. > > Signed-off-by: Gautham R Shenoy > Signed-off-by: Vaidyanathan Srinivasan > --- > > include/linux/sched.h | 11 +++++++++++ > kernel/sched.c | 16 +++++++++++++--- > 2 files changed, 24 insertions(+), 3 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 55e30d1..888f2b2 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -764,6 +764,17 @@ enum cpu_idle_type { > #define SD_SERIALIZE 1024 /* Only a single load balancing instance */ > #define SD_WAKE_IDLE_FAR 2048 /* Gain latency sacrificing cache hit */ > > +enum powersavings_balance_level { > + POWERSAVINGS_BALANCE_NONE = 0, /* No power saving load balance */ > + POWERSAVINGS_BALANCE_BASIC, /* Fill one thread/core/package > + * first for long running threads > + */ > + POWERSAVINGS_BALANCE_WAKEUP, /* Also bias task wakeups to semi-idle > + * cpu package for power savings > + */ > + MAX_POWERSAVINGS_BALANCE_LEVELS > +}; > + > #define BALANCE_FOR_MC_POWER \ > (sched_smt_power_savings ? SD_POWERSAVINGS_BALANCE : 0) > > diff --git a/kernel/sched.c b/kernel/sched.c > index e4bb1dd..322cd2a 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -7879,14 +7879,24 @@ int arch_reinit_sched_domains(void) > static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt) > { > int ret; > + unsigned int level = 0; > > - if (buf[0] != '0' && buf[0] != '1') > + sscanf(buf, "%u", &level); Don't we need to check what sscanf returns? Does a invalid value push the power savings to 0 > + > + /* > + * level is always be positive so don't check for > + * level < POWERSAVINGS_BALANCE_NONE which is 0 > + * What happens on 0 or 1 byte write, > + * need to check for count as well? > + */ See above > + > + if (level >= MAX_POWERSAVINGS_BALANCE_LEVELS) > return -EINVAL; > > if (smt) > - sched_smt_power_savings = (buf[0] == '1'); > + sched_smt_power_savings = level; > else > - sched_mc_power_savings = (buf[0] == '1'); > + sched_mc_power_savings = level; > > ret = arch_reinit_sched_domains(); > > > -- Balbir -- 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/