Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751897AbaKGG0q (ORCPT ); Fri, 7 Nov 2014 01:26:46 -0500 Received: from mail-la0-f52.google.com ([209.85.215.52]:51900 "EHLO mail-la0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751555AbaKGG0o convert rfc822-to-8bit (ORCPT ); Fri, 7 Nov 2014 01:26:44 -0500 MIME-Version: 1.0 In-Reply-To: <20141107060040.GD30507@yliu-dev.sh.intel.com> References: <20141107060040.GD30507@yliu-dev.sh.intel.com> From: Andy Lutomirski Date: Thu, 6 Nov 2014 22:26:23 -0800 Message-ID: Subject: Re: [LKP] [x86_64,entry] f04e05b81e4: -62.7% time.user_time To: LKP Cc: LKML , Yuanhan Liu Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 6, 2014 at 10:00 PM, LKP wrote: > FYI, we noticed the below changes on > > git://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git x86/entry > commit f04e05b81e4d9ae88bee379f12176f551a24394a ("x86_64,entry: Use sysret to return to userspace when possible") > > > f2ee9bebb99dd4a4 f04e05b81e4d9ae88bee379f12 testbox/testcase/testparams > ---------------- -------------------------- > %stddev %change %stddev > \ | \ > 24.09 ± 4% -62.7% 8.99 ± 3% lkp-wsx02/aim9/performance-300s-creat-clo > 24.09 -62.7% 8.99 GEO-MEAN time.user_time > I don't really know how to interpret this. Is this a good thing or a bad thing? I actually expect this change to be a dramatic speedup for some workloads. Any chance you can send me the .config, kernel command line, and whether you have any tracing features enabled? --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/