From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752968Ab1ILIFi (ORCPT ); Mon, 12 Sep 2011 04:05:38 -0400 Received: from mailout-de.gmx.net ([213.165.64.23]:33705 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751831Ab1ILIFh (ORCPT ); Mon, 12 Sep 2011 04:05:37 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1+2bLhLBUi2IAbZLPjsjqnvXZMD8fkGb37aZW0qyq 0sVdgPUQyplveF Subject: Re: [ANNOUNCE] 3.0.4-rt13 From: Mike Galbraith To: Thomas Gleixner Cc: LKML , linux-rt-users In-Reply-To: References: <1315764876.6352.61.camel@marge.simson.net> Content-Type: text/plain; charset="UTF-8" Date: Mon, 12 Sep 2011 10:05:33 +0200 Message-ID: <1315814733.21927.16.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-09-12 at 09:33 +0200, Thomas Gleixner wrote: > On Sun, 11 Sep 2011, Mike Galbraith wrote: > > > I'm very definitely missing sirq threads from the wakeup latency POV. > > > > (Other things are muddying the water, eg. rcu boost, if wired up and > > selected always ramming boosted threads through the roof instead of > > configured boost prio.. etc etc, but this definitely improves my latency > > woes a lot) > > > > This is a giant step backward from "let's improve abysmal throughput", > > so I'm wondering if anyone has better ideas. > > One of the problems we have are the signal based timers (posix-timer, > itimer). That's the biggest part of my jitter troubles. > We really want to move the penalty for those into the context > of the thread/process to which those timers belong. The trick is to > just note the expiry of a timer and wake up the target which has to > deal with the real work in his own context and on his own > account. That's rather simple for thread bound signals, but has a lot > of implications with process wide ones. Though it should be doable and > I'd rather see that solved than hacking around with the split softirqs That definitely sounds like a better idea.. for someone who thoroughly understands signals. > > WRT below: "fixes" are dinky, this is not... > > > > sched, rt, sirq: resurrect sirq threads for RT_FULL > > > > Not-signed-off-by: Mike Galbraith > > Not-that-delighted: tglx Ditto. -Mike