From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932641AbcBANos (ORCPT ); Mon, 1 Feb 2016 08:44:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54550 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932183AbcBANor (ORCPT ); Mon, 1 Feb 2016 08:44:47 -0500 Subject: Re: [PATCH 1/4] sched,time: remove non-power-of-two divides from __acct_update_integrals To: Peter Zijlstra , Thomas Gleixner References: <1454292751-23472-1-git-send-email-riel@redhat.com> <1454292751-23472-2-git-send-email-riel@redhat.com> <20160201092223.GL6357@twins.programming.kicks-ass.net> Cc: linux-kernel@vger.kernel.org, fweisbec@gmail.com, mingo@kernel.org, luto@amacapital.net, clark@redhat.com From: Rik van Riel Message-ID: <56AF614C.4070702@redhat.com> Date: Mon, 1 Feb 2016 08:44:44 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20160201092223.GL6357@twins.programming.kicks-ass.net> 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 On 02/01/2016 04:22 AM, Peter Zijlstra wrote: > On Mon, Feb 01, 2016 at 09:37:00AM +0100, Thomas Gleixner wrote: >> On Sun, 31 Jan 2016, riel@redhat.com wrote: >>> @@ -93,9 +93,9 @@ void xacct_add_tsk(struct taskstats *stats, struct task_struct *p) >>> { >>> struct mm_struct *mm; >>> >>> - /* convert pages-usec to Mbyte-usec */ >>> - stats->coremem = p->acct_rss_mem1 * PAGE_SIZE / MB; >>> - stats->virtmem = p->acct_vm_mem1 * PAGE_SIZE / MB; >>> + /* convert pages-nsec/1024 to Mbyte-usec, see __acct_update_integrals */ >>> + stats->coremem = p->acct_rss_mem1 * PAGE_SIZE / (1000 * KB); >>> + stats->virtmem = p->acct_vm_mem1 * PAGE_SIZE / (1000 * KB); >> >> You replace "/ (1024 * 1024)" by "/ (1000 * 1024). So that's introducing a non >> power of 2 division instead of removing one and wont compile on systems which >> do not have a 64/32 division in hardware. > > Yep, so that needs to be fixed to use do_div(). But the reason for this > is that this is the consumer side of these stats and therefore rarely > executed. Before I send in a v4 with do_div in that location, are there any other changes you would like me to make to the code? -- All rights reversed