From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932183Ab3D3LLY (ORCPT ); Tue, 30 Apr 2013 07:11:24 -0400 Received: from mail-bk0-f46.google.com ([209.85.214.46]:44512 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760213Ab3D3LLX (ORCPT ); Tue, 30 Apr 2013 07:11:23 -0400 Date: Tue, 30 Apr 2013 13:11:19 +0200 From: Ingo Molnar To: Stanislaw Gruszka Cc: Peter Zijlstra , Frederic Weisbecker , hpa@zytor.com, rostedt@goodmis.org, akpm@linux-foundation.org, tglx@linutronix.de, Linus Torvalds , linux-kernel@vger.kernel.org, Dave Hansen Subject: Re: [PATCH -tip 1/4] sched: Avoid cputime scaling overflow Message-ID: <20130430111119.GA28821@gmail.com> References: <1367314507-9728-1-git-send-email-sgruszka@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1367314507-9728-1-git-send-email-sgruszka@redhat.com> 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 * Stanislaw Gruszka wrote: > Here is patch, which add Linus cputime scaling algorithm to the kernel. > > This is follow up of commit d9a3c9823a2e6a543eb7807fb3d15d8233817ec5 > "sched: Lower chances of cputime scaling overflow" which try to avoid > multiplication overflow, but not guarantee that the overflow will not > happen. > > Linus crated different algorithm, which avoid completely multiplication > overflow by dropping precision when numbers are big. It was tested > by me and it gives good relative error of scaled numbers. > > Signed-off-by: Stanislaw Gruszka For multi-authored code it's generally nice to add a tag like this: Originally-From: Linus Torvalds It would also be nice to quote the testing results/output and the precision estimations in the changelog - so that others can see the code's current capabilities and limitations. Thanks, Ingo