From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762304AbYETIK2 (ORCPT ); Tue, 20 May 2008 04:10:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757733AbYETIKO (ORCPT ); Tue, 20 May 2008 04:10:14 -0400 Received: from mga10.intel.com ([192.55.52.92]:37300 "EHLO fmsmga102.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756426AbYETIKM (ORCPT ); Tue, 20 May 2008 04:10:12 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.27,514,1204531200"; d="scan'208";a="330218816" Subject: hackbench regression with 2.6.26-rc2 on tulsa machine From: "Zhang, Yanmin" To: Mike Galbraith Cc: Peter Zijlstra , LKML Content-Type: text/plain; charset=UTF-8 Date: Tue, 20 May 2008 16:09:06 +0800 Message-Id: <1211270946.3177.236.camel@ymzhang> Mime-Version: 1.0 X-Mailer: Evolution 2.21.5 (2.21.5-2.fc9) Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Comparing with 2.6.26-rc1, hackbench has about 30% regression with 2.6.26-rc2 on my tulsa machine which is a netburst architecure hyper-threading x86_64. Command line to test: #hackbench 100 process 2000 With 2.6.26-rc1, it takes 30 seconds. But with 2.6.26-rc2/rc3, it takes 40 seconds. Bisect located below patch: 46151122e0a2e80e5a6b2889f595e371fe2b600d is first bad commit commit 46151122e0a2e80e5a6b2889f595e371fe2b600d Author: Mike Galbraith Date: Thu May 8 17:00:42 2008 +0200 sched: fix weight calculations The conversion between virtual and real time is as follows: dvt = rw/w * dt <=> dt = w/rw * dvt Since we want the fair sleeper granularity to be in real time, we actually need to do: dvt = - rw/w * l The bisect steps look stable. On my core architecure machines(stoakley and tigerton), I do see improvement instead of regression, like result from 31 seconds down to 28 seconds. I'm not sure if hyper-threading need more cares in this situation. -yanmin