Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758462Ab0G3LYP (ORCPT ); Fri, 30 Jul 2010 07:24:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40613 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756305Ab0G3LYO (ORCPT ); Fri, 30 Jul 2010 07:24:14 -0400 Date: Fri, 30 Jul 2010 13:23:43 +0200 From: Stanislaw Gruszka To: Tomasz Buchert Cc: linux-kernel@vger.kernel.org, Daniel Walker , Peter Zijlstra Subject: Re: [PATCH 0/4] Wall time clocks + change in access rules Message-ID: <20100730132343.4c15bfdc@dhcp-lab-109.englab.brq.redhat.com> In-Reply-To: <1280483867-6387-1-git-send-email-tomasz.buchert@inria.fr> References: <1280483867-6387-1-git-send-email-tomasz.buchert@inria.fr> Organization: RedHat Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1381 Lines: 32 Hi Tomasz On Fri, 30 Jul 2010 11:57:43 +0200 Tomasz Buchert wrote: > During our work we encountered a problem of obtaining > a reliable and fine-grained measurements of CPU time/wall time > of a process/thread. The existing methods (taskstats, procfs, > POSIX CPU clocks) have either unfriendly interface (taskstats) Well, "unfriendly" is not technical word ... Taskstat was designed as extensible method to provide statistics to user space, including some special needs like yours. What your patches basically do, is get the value of wall_time(p) = uptime - p->start_time . I do not see any reason why this calculation can not be done in userspace, getting uptime and p->start_time from kernel by existing methods (or adding new one for p->start_time if precise method does not really exist). Is enough to read p->start_time only once at the beginning, this value does not change. Anyway, I think we need better rationale, before we can consider your wall clock patches inclusion into the kernel. BTW: If you will repost please cc Thomas Gleixner as he is kernel/*timers* maintainer. Cheers Stanislaw -- 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/