From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44C4BC33CAA for ; Mon, 20 Jan 2020 10:04:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2614F2087E for ; Mon, 20 Jan 2020 10:04:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727005AbgATKEy (ORCPT ); Mon, 20 Jan 2020 05:04:54 -0500 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:40616 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726075AbgATKEy (ORCPT ); Mon, 20 Jan 2020 05:04:54 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04446;MF=wenyang@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0ToE0t8W_1579514685; Received: from localhost(mailfrom:wenyang@linux.alibaba.com fp:SMTPD_---0ToE0t8W_1579514685) by smtp.aliyun-inc.com(127.0.0.1); Mon, 20 Jan 2020 18:04:51 +0800 From: Wen Yang To: Paolo Valente Cc: Wen Yang , Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] block, bfq: improve arithmetic division in bfq_delta() Date: Mon, 20 Jan 2020 18:04:43 +0800 Message-Id: <20200120100443.45563-1-wenyang@linux.alibaba.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org do_div() does a 64-by-32 division. Use div64_ul() instead of it if the divisor is unsigned long, to avoid truncation to 32-bit. And as a nice side effect also cleans up the function a bit. Signed-off-by: Wen Yang Cc: Paolo Valente Cc: Jens Axboe Cc: linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- block/bfq-wf2q.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c index 05f0bf4a1144..ffe9ce9faa89 100644 --- a/block/bfq-wf2q.c +++ b/block/bfq-wf2q.c @@ -277,10 +277,7 @@ struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity) */ static u64 bfq_delta(unsigned long service, unsigned long weight) { - u64 d = (u64)service << WFQ_SERVICE_SHIFT; - - do_div(d, weight); - return d; + return div64_ul((u64)service << WFQ_SERVICE_SHIFT, weight); } /** -- 2.23.0