From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752547AbYGaKxo (ORCPT ); Thu, 31 Jul 2008 06:53:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750828AbYGaKxg (ORCPT ); Thu, 31 Jul 2008 06:53:36 -0400 Received: from [218.94.130.82] ([218.94.130.82]:1142 "HELO mail.archermind.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with SMTP id S1750752AbYGaKxg (ORCPT ); Thu, 31 Jul 2008 06:53:36 -0400 X-Greylist: delayed 916 seconds by postgrey-1.27 at vger.kernel.org; Thu, 31 Jul 2008 06:53:35 EDT Message-ID: <4891960E.2000605@archermind.com> Date: Thu, 31 Jul 2008 18:38:06 +0800 From: richard User-Agent: Thunderbird 2.0.0.4 (X11/20071018) MIME-Version: 1.0 To: linux-kernel@vger.kernel.org CC: torvalds@linux-foundation.org, akpm@linux-foundation.org Subject: kernel performance issue Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 31 Jul 2008 10:38:27.0363 (UTC) FILETIME=[91017730:01C8F2F9] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi: I have a question about the kernel performance of kernel 2.6.24. I use "time" to account the time cost of "date" execution, and find that the "real time" of kernel 2.6.24 is always bigger than kernel 2.6.21 on my arm board. For my understanding, the time cost of 2.6.24 shouldn't be bigger than 2.6.21, because it is a upgrade of 2.6.21 and the its performance should be better than 2.6.21, if I am wrong please let me know. [root@Linux /root]#cat ./date-loop.sh #! /bin/sh loop=1 while [ $loop -le 50 ] do date +%s loop=$(($loop+1)) done Time cost in kernel 2.6.24: [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.06s sys 0m 0.43s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.07s sys 0m 0.42s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.09s sys 0m 0.40s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.07s sys 0m 0.41s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.07s sys 0m 0.42s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.09s sys 0m 0.40s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.06s sys 0m 0.43s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.08s sys 0m 0.41s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.09s sys 0m 0.40s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.10s sys 0m 0.39s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.05s sys 0m 0.44s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.05s sys 0m 0.44s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.09s sys 0m 0.40s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.07s sys 0m 0.42s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.07s sys 0m 0.42s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.48s user 0m 0.09s sys 0m 0.40s [root@Linux /root]# Time cost in kernel 2.6.21: [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.08s sys 0m 0.38s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.07s sys 0m 0.39s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.09s sys 0m 0.37s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.09s sys 0m 0.37s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.08s sys 0m 0.38s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.06s sys 0m 0.40s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.09s sys 0m 0.37s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.10s sys 0m 0.36s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.04s sys 0m 0.42s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.09s sys 0m 0.37s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.07s sys 0m 0.39s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.08s sys 0m 0.38s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.10s sys 0m 0.36s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.09s sys 0m 0.37s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.09s sys 0m 0.37s [root@Linux /root]#time ./date-loop.sh > /dev/null real 0m 0.45s user 0m 0.07s sys 0m 0.39s [root@Linux /root]# -- Best Regards, Yang Lu