From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751313AbcBLOgX (ORCPT ); Fri, 12 Feb 2016 09:36:23 -0500 Received: from krieglstein.org ([176.28.13.145]:40596 "EHLO lvps176-28-13-145.dedicated.hosteurope.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750820AbcBLOgV convert rfc822-to-8bit (ORCPT ); Fri, 12 Feb 2016 09:36:21 -0500 From: Tim Sander To: Sebastian Andrzej Siewior Cc: linux-rt-users , LKML , Thomas Gleixner , rostedt@goodmis.org, John Kacur Subject: Re: [ANNOUNCE] 4.1.5-rt5 meant to reply to 4.4.1-rt5 Date: Fri, 12 Feb 2016 15:36:16 +0100 Message-ID: <7138155.u6nNkmxGuH@dabox> Organization: Sander and Lightning User-Agent: KMail/4.14.3 (Linux/4.4.0-00001-g95803be; KDE/4.14.13; x86_64; ; ) In-Reply-To: <56BDA0EF.7090503@linutronix.de> References: <20150816135630.GE7004@linutronix.de> <1614199.PesBpXyHut@dabox> <56BDA0EF.7090503@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="iso-8859-1" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sebastian As you got correctly i was talking about 4.4.1-rt5 and not 4.1 i replied to by accident. Am Freitag, 12. Februar 2016, 10:07:59 schrieb Sebastian Andrzej Siewior: > On 02/12/2016 09:28 AM, Tim Sander wrote: > > Hi Sebastian > > Hi Tim, > > > Am Sonntag, 16. August 2015, 15:56:30 schrieb Sebastian Andrzej Siewior: > >> I'm pleased to announce the v4.1.5-rt5 patch set. > > > > I have just tested it with a Altera SoC ARM v7. The latencies seem to have > > gotten a little bit worse with each release. The first core has always > > been > > worse (presumably due to interrupt load) but now it dropped to 111µs (rt5) > > from 76µs(rt3) and 54µs(rt2). > > in -rt2 we had bug in migrate disable code which means each task was > running on CPU0. This got partly fixed in -rt3. In -rt3 the scheduler > could assign a task to CPU1 but the task should stay there for ever. > This little detail was fixed in -rt5. > This is one thing that comes to mind. > Lazy-preempt should have been fixed in -rt3, too. This should not give > you higher latencies but higher throughput. > > What about rt4? It is only the stable update so you should see here the > numbers from rt3. If that is true and your numbers are stable it should > be easy to run git bisect between rt4 and rt5. And looking at > https://git.kernel.org/rt/linux-rt-devel/h/v4.4.1-rt5 > the only non-cosmetic change in -rt5 that should affect you is the > migrate-disable fixup from Mike. Ok, each run takes a couple of hours so bisecting should take quite some time but i will give it a try. I started a test with 4.4.1-rt4, if the numbers are within the 70µs ballpark bisecting seems the way to go. If the numbers are higher i suspect that stable update might have a play here. But we will see. Best regards Tim