Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932244Ab3CYOkw (ORCPT ); Mon, 25 Mar 2013 10:40:52 -0400 Received: from a192-166.smtp-out.amazonses.com ([199.255.192.166]:4383 "EHLO a192-166.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757002Ab3CYOkv (ORCPT ); Mon, 25 Mar 2013 10:40:51 -0400 X-Greylist: delayed 558 seconds by postgrey-1.27 at vger.kernel.org; Mon, 25 Mar 2013 10:40:51 EDT Date: Mon, 25 Mar 2013 14:31:32 +0000 From: Christoph Lameter X-X-Sender: cl@gentwo.org To: "Paul E. McKenney" cc: Steven Rostedt , Frederic Weisbecker , Rob Landley , linux-kernel@vger.kernel.org, josh@joshtriplett.org, zhong@linux.vnet.ibm.com, khilman@linaro.org, geoff@infradead.org, tglx@linutronix.de Subject: Re: [PATCH] nohz1: Documentation In-Reply-To: <20130322162820.GN3637@linux.vnet.ibm.com> Message-ID: <0000013da1f6170e-7b247826-93a9-4c2d-a316-ba3b0597a805-000000@email.amazonses.com> References: <20130318222548.GG3656@linux.vnet.ibm.com> <1363822338.6345.33.camel@gandalf.local.home> <20130320235545.GL3637@linux.vnet.ibm.com> <0000013d8db514e4-bf492080-82c9-412a-90b8-54ddc1463e4b-000000@email.amazonses.com> <20130321171518.GW3637@linux.vnet.ibm.com> <0000013d8e3f58ce-0f6ea95f-780a-49c1-a633-5aa0cf3e5040-000000@email.amazonses.com> <20130321185821.GF3637@linux.vnet.ibm.com> <0000013d8e8d24fd-d2931c45-2722-46d1-8b47-2ef11e21096d-000000@email.amazonses.com> <20130321205054.GI3637@linux.vnet.ibm.com> <0000013d9289cebc-e6380265-3a74-4343-b851-765f785a3754-000000@email.amazonses.com> <20130322162820.GN3637@linux.vnet.ibm.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SES-Outgoing: 199.255.192.166 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1006 Lines: 23 On Fri, 22 Mar 2013, Paul E. McKenney wrote: > On Fri, Mar 22, 2013 at 02:38:58PM +0000, Christoph Lameter wrote: > > On Thu, 21 Mar 2013, Paul E. McKenney wrote: > > > > > So, how long of busy periods are you contemplating for your SCHED_FIFO > > > threads? Is it possible to tune/adjust the offending per-CPU ktheads > > > to wake up less frequently than that time? > > > > Test programs right now run 10 seconds. 30 seconds would definitely be > > enough for the worst case. > > OK, that might be doable for some workloads. What happens when you > try tuning the 2-second wakeup interval to (say) 45 seconds? The vm kernel threads do no useful work if no system calls are being done. If there is no kernel action then they can be deferred indefinitely. -- 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/