From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751885Ab1JIO1G (ORCPT ); Sun, 9 Oct 2011 10:27:06 -0400 Received: from mail-qw0-f46.google.com ([209.85.216.46]:36433 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751422Ab1JIO1C (ORCPT ); Sun, 9 Oct 2011 10:27:02 -0400 In-Reply-To: <1318140213.6216.40.camel@marge.simson.net> References: <35C27021-40FC-4127-BC82-9F86FA9D624A@gmail.com> <1318140213.6216.40.camel@marge.simson.net> Mime-Version: 1.0 (Apple Message framework v753.1) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <8AF29618-6746-484D-B773-AED31FBA714D@gmail.com> Cc: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 7bit From: Robert Kubrick Subject: Re: 2.6.32 / RH 6.1 scheduler bloated Date: Sun, 9 Oct 2011 10:26:22 -0400 To: Mike Galbraith X-Mailer: Apple Mail (2.753.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Will try this, but I have older kernel version running on the same hardware, with the same boot parameters, and showing a more reasonable 2us wakeup latency. Still high, but coming out of idle can be slow as you say. But 10us?? On Oct 9, 2011, at 2:03 AM, Mike Galbraith wrote: > On Sat, 2011-10-08 at 20:26 -0400, Robert Kubrick wrote: >> A simple ftrace wakeup test shows 10us latency during the idle-to-run >> transition: > > If you boot nohz=off idle=poll, and measure with cyclictest > (measure in > userspace for free), you'll likely see a remarkable difference. > > Coming out of idle can be slow, but that has more to do with silicon > than scheduler bloat (not that bloat doesn't exist mind you). My > Q6600 > box _sucks_ at getting off it's duff, even intel_idle.max_cstate=1 is > horrid. E5620 gets moving > order of magnitude more quickly with the > same kernel/config/params. > > -Mike >