Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965034Ab3DJMvR (ORCPT ); Wed, 10 Apr 2013 08:51:17 -0400 Received: from mail-ea0-f171.google.com ([209.85.215.171]:44150 "EHLO mail-ea0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964987Ab3DJMvQ (ORCPT ); Wed, 10 Apr 2013 08:51:16 -0400 Date: Wed, 10 Apr 2013 14:51:11 +0200 From: Ingo Molnar To: Frederic Weisbecker Cc: Stanislaw Gruszka , Peter Zijlstra , linux-kernel@vger.kernel.org, hpa@zytor.com, rostedt@goodmis.org, akpm@linux-foundation.org, tglx@linutronix.de, linux-tip-commits@vger.kernel.org, Linus Torvalds Subject: Re: [tip:sched/core] sched: Lower chances of cputime scaling overflow Message-ID: <20130410125111.GA12923@gmail.com> References: <20130326140147.GB2029@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 666 Lines: 18 * Frederic Weisbecker wrote: > Of course 128 bits ops are very expensive, so to help you evaluating the > situation, this is going to happen on every call to task_cputime_adjusted() and > thread_group_adjusted(), namely: It's really only expensive for divisions. Addition and multiplication should be straightforward and relatively low overhead, especially on 64-bit platforms. Thanks, Ingo -- 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/