From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754325AbbGFSTf (ORCPT ); Mon, 6 Jul 2015 14:19:35 -0400 Received: from mail-pd0-f182.google.com ([209.85.192.182]:33195 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751364AbbGFSTd (ORCPT ); Mon, 6 Jul 2015 14:19:33 -0400 From: Afzal Mohammed To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , Afzal Mohammed Subject: [PATCH v2] sched,fair: Remove > u32 weight handling for delta Date: Mon, 6 Jul 2015 23:49:15 +0530 Message-Id: <1436206755-2540-1-git-send-email-afzal.mohd.ma@gmail.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <20150706133407.GA5861@afzalpc> References: <20150706133407.GA5861@afzalpc> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org scaled down weight 'fact' would not be > u32 rather than unlikely as the weight being passed in __calc_delta() is either 'se->load.weight' or NICE_O_LOAD. 'se->load.weight' would be one of the values of prio_to_weight[] in the case of task, while in the case of task group it would be capped to MAX_SHARES. All those possible values can fit in u32. Hence remove the initial > u32 handling on 'fact'. Signed-off-by: Afzal Mohammed --- v2: expand change log on why weight can fit in u32, remove incorrect comments. kernel/sched/fair.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 65c8f3ebdc3c..22cf3958bbac 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -218,13 +218,6 @@ static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight __update_inv_weight(lw); - if (unlikely(fact >> 32)) { - while (fact >> 32) { - fact >>= 1; - shift--; - } - } - /* hint to use a 32x32->64 mul */ fact = (u64)(u32)fact * lw->inv_weight; -- 2.1.4