From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754298AbaICSi7 (ORCPT ); Wed, 3 Sep 2014 14:38:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38892 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751632AbaICSi6 (ORCPT ); Wed, 3 Sep 2014 14:38:58 -0400 Message-ID: <54076022.80202@redhat.com> Date: Wed, 03 Sep 2014 14:38:26 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: Andrew Theurer CC: linux-kernel@vger.kernel.org, oleg@redhat.com, peterz@infradead.org, umgwanakikbuti@gmail.com, fweisbec@gmail.com, akpm@linux-foundation.org, srao@redhat.com, lwoodman@redhat.com, Peter Zijlstra , Andrew Morton , Ingo Molnar Subject: Re: [PATCH 0/3] lockless sys_times and posix_cpu_clock_get References: <1408133138-22048-1-git-send-email-riel@redhat.com> <198309898.21797553.1408483311099.JavaMail.zimbra@redhat.com> In-Reply-To: <198309898.21797553.1408483311099.JavaMail.zimbra@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 08/19/2014 05:21 PM, Andrew Theurer wrote: > >> Thanks to the feedback from Oleg, Peter, Mike, and Frederic, I >> seem to have a patch series that manages to do times() >> locklessly, and apparently correctly. > > >> >> Oleg points out that the monotonicity alone is not enough of a >> guarantee, but that should probably be attacked separately, >> since that issue is equally present with and without these >> patches... >> >> The test case below, slightly changed from the one posted by >> Spencer Candland in 2009, now runs in 11 seconds instead of 5 >> minutes. >> >> Is it worthwhile? There apparently are some real workloads that >> call times() a lot, and I believe Sanjay and Andrew have one >> sitting around. > > Thanks for doing this. When running a OLTP workload in a KVM VM, > we saw a 71% increase in performance! do_sys_times() was a big > bottleneck for us. Thanks Andrew, a 71% performance increase seems like it would be enough to justify merging these patches... Peter, Ingo, Andrew, Do any of you have an objection to these patches? Which tree should I merge them through? I am happy to resubmit them against any tree, just let me know where you want the patches to go. thanks, Rik - -- All rights reversed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUB2AiAAoJEM553pKExN6DlKsH/RygM0SAcKcqbhk7qbKgQsFI fe9mzJeDg5X2OVW1LuKKhpdo0wPiJ6arg3s2kWnJ8YuToMlIYjFwh9V+fwk1p7bV 4X8KYEK1DyJux8ZYwOBXlZORL+mE30scwuOF8B0sY+TepiRHeorv0srTIXgJfGyJ avv95X/hx5JSqjAeRomHPmIX8VzgbHTXPEzWxVj+64qehI63CqyLGXXSlHPvFL4D uhIRvCC4WxKNldUX20HZFUlQETsJttWoM14SiT1HZbfZNJxDMkD6kjcNl7Uimw9j gVQeE4qy5OkdY1RSsVN35mg+mGA8kzUoQV0aEkogXwbJYNB+wFQ7OEupA1BKiGw= =6lUC -----END PGP SIGNATURE-----