From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751876AbbGFOjl (ORCPT ); Mon, 6 Jul 2015 10:39:41 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:33854 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750945AbbGFOjj (ORCPT ); Mon, 6 Jul 2015 10:39:39 -0400 Date: Mon, 6 Jul 2015 20:09:20 +0530 From: Afzal Mohammed To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Ingo Molnar Subject: Re: [PATCH] sched,fair: Remove > u32 weight handling for delta Message-ID: <20150706143920.GA2704@afzalpc> References: <1436150677-1818-1-git-send-email-afzal.mohd.ma@gmail.com> <20150706114430.GE3644@twins.programming.kicks-ass.net> <20150706133407.GA5861@afzalpc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150706133407.GA5861@afzalpc> 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 Hi, On Mon, Jul 06, 2015 at 07:04:07PM +0530, Afzal Mohammed wrote: > On Mon, Jul 06, 2015 at 01:44:30PM +0200, Peter Zijlstra wrote: > > On Mon, Jul 06, 2015 at 08:14:37AM +0530, Afzal Mohammed wrote: > > > The hunk being removed here > > > would not make a difference to it as this is on scaled weight > u32. > > > And pre-"9dbdb15553239" doesn't seem to have logical equivalent of hunk > > > removed here either. > > > > -ENOPARSE. > > Reading 9dbdb15553239 ("sched/fair: Rework sched_fair time > accounting") again, realized that I am wrong on this, that was > referring to the below statement removed in that commit, > > if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION))) > tmp = (u64)delta_exec * scale_load_down(weight); > > earlier came to a reasoning that as scale_load_down(weight) was not > separately typecasted, value above u32 would be discarded, that non > parsable statement meant that weight > u32 was not considered. Since > cast has precedence over multiply, that statement of mine was wrong. I take that back, consider as though I have not mentioned anything above :) Regards Afzal