Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761888AbYFWRyT (ORCPT ); Mon, 23 Jun 2008 13:54:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755908AbYFWRyE (ORCPT ); Mon, 23 Jun 2008 13:54:04 -0400 Received: from e4.ny.us.ibm.com ([32.97.182.144]:57219 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755191AbYFWRyD (ORCPT ); Mon, 23 Jun 2008 13:54:03 -0400 Subject: Re: [PATCH -tip-rcu] Make rcutorture more vicious: make quiescent rcutorture less power-hungry From: Darren Hart To: Arjan van de Ven Cc: paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, mingo@elte.hu, josh@freedesktop.org, niv@us.ibm.com, dino@in.ibm.com, akpm@linux-foundation.org, torvalds@linux-foundation.org, vegard.nossum@gmail.com, adobriyan@gmail.com, oleg@tv-sign.ru, bunk@kernel.org, rjw@sisk.pl In-Reply-To: <20080622131712.54ba732c@infradead.org> References: <20080618122144.GA27143@linux.vnet.ibm.com> <20080618162649.GA18326@linux.vnet.ibm.com> <20080622200638.GA25328@linux.vnet.ibm.com> <20080622131712.54ba732c@infradead.org> Content-Type: text/plain Date: Mon, 23 Jun 2008 17:54:09 +0000 Message-Id: <1214243649.4440.10.camel@Aeon> Mime-Version: 1.0 X-Mailer: Evolution 2.22.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2127 Lines: 55 On Sun, 2008-06-22 at 13:17 -0700, Arjan van de Ven wrote: > On Sun, 22 Jun 2008 13:06:38 -0700 > "Paul E. McKenney" wrote: > > > This patch makes the non-module rcutorture a bit more friendly to > > the power-conservation code. This is a rather simple-minded approach. > > More sophisticated approaches would get rid of the rcutorture tasks > > while rcutorture execution was suppressed, but attempts thus far to > > do this have not gone well -- calling rcu_torture_init() from a /proc > > callout results in oopses. > > > > Signed-off-by: Paul E. McKenney > > --- > > > > rcutorture.c | 5 ++++- > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > diff -urpNa -X dontdiff > > linux-2.6.26-rc4-rcut2-proc/kernel/rcutorture.c > > linux-2.6.26-rc4-rcut3-procq/kernel/rcutorture.c --- > > linux-2.6.26-rc4-rcut2-proc/kernel/rcutorture.c 2008-06-22 > > 10:29:04.000000000 -0700 +++ > > linux-2.6.26-rc4-rcut3-procq/kernel/rcutorture.c 2008-06-22 > > 12:20:10.000000000 -0700 @@ -196,7 +196,10 @@ static void > > rcu_stutter_wait(void) { while (stutter_pause_test > > || !rcutorture_runnable) > > - schedule_timeout_interruptible(1); > > + if (rcutorture_runnable) > > + schedule_timeout_interruptible(1); > > + else > > + schedule_timeout_interruptible(HZ); > > } > > could you also make it use round_jiffies_relative() to make the power > impact even less..... > (by coalescing various "once a second" timers like this) I'm a little concerned about how this will affect real-time performance, as queueing up lots of timers all at once can lead to long running timer expiration handlers. If just a schedule_timeout, I suppose we are only looking at a process wakeup, as opposed to a softirq context callback function? Thanks, -- Darren Hart Real-Time Linux Team Lead IBM Linux Technology Center -- 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/