From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751793AbXDIJUU (ORCPT ); Mon, 9 Apr 2007 05:20:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751821AbXDIJUU (ORCPT ); Mon, 9 Apr 2007 05:20:20 -0400 Received: from wx-out-0506.google.com ([66.249.82.234]:6309 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751793AbXDIJUS (ORCPT ); Mon, 9 Apr 2007 05:20:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=ptoRiPue7sqy4nSs/UsUYkYn3JVk/1pxsOGgVEsnQKI/8U7U3l62ZVkN0Gd9uW6LtrFERPRv8yHcuYZPgeL6aIVJXFGaMMqgG8uDUBxQaZInhAlWX50gGFGevUPjv5R5dxQseHeOkPL+uuPiDAJnk0Ej6HUWaLSvuK0gKwioqyk= Message-ID: Date: Mon, 9 Apr 2007 11:20:16 +0200 From: "Dmitry Adamushko" To: "Mike Galbraith" Subject: Re: SD scheduler testing hitch Cc: "Linux Kernel" In-Reply-To: <1176099797.6355.122.camel@Homer.simpson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200704082134.43029.a1426z@gawab.com> <1176099797.6355.122.camel@Homer.simpson.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 09/04/07, Mike Galbraith wrote: > On Sun, 2007-04-08 at 21:34 +0300, Al Boldi wrote: > > Mike Galbraith wrote: > > > On Sat, 2007-04-07 at 19:17 +0200, Mike Galbraith wrote: > > > > I lowered the time to 500us, and ran at nice -10.. it starves tenpercent > > > > here every time. (ran as taskset -c 1 nice -n -10 ./fairtest) The > > > > starving 10% duty cycle task has trouble getting 1% CPU. > > > > > > Hmm. Playing with it some more today, it still happens, but it's not > > > very repeatable. Something is odd. I wonder if any SD using readers > > > will try it. > > > > Tried it on mainline 2.6.20.3. > > It's not easily repeatable, but it's got the same problem. In my case, it's easily reproducible. Below is a mainline 2.6.19. Look at both %CPU and TIME+ (sched_time). top - 10:55:00 up 33 min, 8 users, load average: 1.07, 0.61, 0.51 Tasks: 76 total, 2 running, 74 sleeping, 0 stopped, 0 zombie Cpu(s): 76.0% us, 0.3% sy, 0.0% ni, 23.7% id, 0.0% wa, 0.0% hi, 0.0% si Mem: 256592k total, 251888k used, 4704k free, 46516k buffers Swap: 272120k total, 4924k used, 267196k free, 90048k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 8113 dimm 15 0 1460 436 360 R 74.4 0.2 1:43.63 fairtest_xx 8114 dimm 15 0 1460 108 32 S 0.3 0.0 0:00.15 fairtest_xx If you take a look at my previous report, you'll also notice "strangeness" with both cpu% and sched_time. sched_clock() is based on "tsc" and it's available for my CPU. So maybe something fishy is going on with accounting. I just wonder, why it's so easily reproducible in my case for both mainline and SD (besides a 2.6.13 mainline, but I have to re-run all the tests letting tenp run longer for the "sched_time" to be accumulated)... -- Best regards, Dmitry Adamushko