From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH V5 0/5] Queue work on power efficient wq Date: Mon, 8 Jul 2013 17:37:16 +0200 Message-ID: <20130708153716.GF29556@pengutronix.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: tj@kernel.org, davem@davemloft.net, airlied@redhat.com, axboe@kernel.dk, tglx@linutronix.de, peterz@infradead.org, mingo@redhat.com, rostedt@goodmis.org, linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, robin.randhawa@arm.com, Steve.Bannister@arm.com, Livi@jasper.es To: Viresh Kumar Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:57303 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751245Ab3GHPhl (ORCPT ); Mon, 8 Jul 2013 11:37:41 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: Hello, On Wed, Apr 24, 2013 at 05:12:52PM +0530, Viresh Kumar wrote: > This patchset was called: "Create sched_select_cpu() and use it for w= orkqueues" > for the first three versions. >=20 > Earlier discussions over v3, v2 and v1 can be found here: > https://lkml.org/lkml/2013/3/18/364 > http://lists.linaro.org/pipermail/linaro-dev/2012-November/014344.htm= l > http://www.mail-archive.com/linaro-dev@lists.linaro.org/msg13342.html >=20 > V4 is here: > https://lkml.org/lkml/2013/3/31/55 >=20 > Workqueues can be performance or power oriented. For performance we m= ay want to > keep them running on a single cpu, so that it remains cache hot. For = power we > can give scheduler the liberty to choose target cpu for running work = handler. >=20 > Later one (Power oriented WQ) can be achieved if the workqueue is all= ocated with > WQ_UNBOUND flag. Enabling CONFIG_WQ_POWER_EFFICIENT will set > 'wq_power_efficient' to 'true'. Setting 'power_efficient' boot param = will > override value of 'wq_power_efficient' variable. When 'wq_power_effic= ient' is > set to 'true', we will convert WQ_POWER_EFFICIENT flag to WQ_UNBOUND = on wq > allocation. And so scheduler will have the liberty to choose where to= run this > work. >=20 > Here we are migrating few users of workqueues to WQ_POWER_EFFICIENT. = These > drivers are found to be very much active on idle or lightly busy syst= em and > using WQ_POWER_EFFICIENT for these gave impressive results. >=20 > These would be used in power saving mode only if relevant configs are= enabled > at compile time or in bootargs. Otherwise behavior is unchanged. >=20 > Setup: > ----- > - ARM Vexpress TC2 - big.LITTLE CPU > - Core 0-1: A15, 2-4: A7 > - rootfs: linaro-ubuntu-devel This patch set hit my tree now. I wonder if it makes sense to make WQ_POWER_EFFICIENT_DEFAULT depend on SMP. (Oh wait, big.LITTLE isn't SMP, so probably there is a better symbol to depend on?) Just my 2 cent Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= | -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html