Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754808Ab3DKUKD (ORCPT ); Thu, 11 Apr 2013 16:10:03 -0400 Received: from casper.infradead.org ([85.118.1.10]:54883 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754052Ab3DKUKB (ORCPT ); Thu, 11 Apr 2013 16:10:01 -0400 Message-ID: <51671878.9050800@infradead.org> Date: Thu, 11 Apr 2013 13:09:28 -0700 From: Randy Dunlap User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, Borislav Petkov , Arjan van de Ven , Kevin Hilman , Christoph Lameter Subject: Re: [PATCH documentation 2/2] kthread: Document ways of reducing OS jitter due to per-CPU kthreads References: <20130411160524.GA30384@linux.vnet.ibm.com> <1365696359-30958-1-git-send-email-paulmck@linux.vnet.ibm.com> <1365696359-30958-2-git-send-email-paulmck@linux.vnet.ibm.com> <5166F062.2090007@infradead.org> <20130411184053.GN29861@linux.vnet.ibm.com> In-Reply-To: <20130411184053.GN29861@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2412 Lines: 70 On 04/11/13 11:40, Paul E. McKenney wrote: > On Thu, Apr 11, 2013 at 10:18:26AM -0700, Randy Dunlap wrote: >> On 04/11/2013 09:05 AM, Paul E. McKenney wrote: >>> From: "Paul E. McKenney" >>> >>> The Linux kernel uses a number of per-CPU kthreads, any of which might >>> contribute to OS jitter at any time. The usual approach to normal >>> kthreads, namely to affinity them to a "housekeeping" CPU, does not >> >> ugh. to affine them > > How about s/affinity/bind/ instead? Yes, that's good. >>> work with these kthreads because they cannot operate correctly if moved >>> to some other CPU. This commit therefore lists ways of controlling OS >>> jitter from the Linux kernel's per-CPU kthreads. >>> >>> Signed-off-by: Paul E. McKenney >>> Cc: Frederic Weisbecker >>> Cc: Steven Rostedt >>> Cc: Borislav Petkov >>> Cc: Arjan van de Ven >>> Cc: Kevin Hilman >>> Cc: Christoph Lameter >>> --- >>> Documentation/kernel-per-CPU-kthreads.txt | 159 ++++++++++++++++++++++++++++++ >>> 1 file changed, 159 insertions(+) >>> create mode 100644 Documentation/kernel-per-CPU-kthreads.txt >>> >>> diff --git a/Documentation/kernel-per-CPU-kthreads.txt b/Documentation/kernel-per-CPU-kthreads.txt >>> new file mode 100644 >>> index 0000000..495dacf >>> --- /dev/null >>> +++ b/Documentation/kernel-per-CPU-kthreads.txt >>> @@ -0,0 +1,159 @@ >>> +REDUCING OS JITTER DUE TO PER-CPU KTHREADS >>> + >>> + >>> +Name: irq/%d-%s >>> +Purpose: Handle threaded interrupts. >>> +To reduce corresponding OS jitter, do the following: >>> +1. Use irq affinity to force the irq threads to execute on >>> + some other CPU. >> >> It would be very nice to explain here how that is done. > > Documentation/IRQ-affinity.txt > > I added a pointer to this near the beginning. > Good. > Thank you for your review and comments! Given my rationale above, > are you still comfortable with my applying your Reviewed-by? Sure. Thanks. >> Reviewed-by: Randy Dunlap -- ~Randy -- 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/