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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 CF5BAC3279B for ; Sat, 30 Jun 2018 12:03:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 814A6249FE for ; Sat, 30 Jun 2018 12:03:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 814A6249FE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=davemloft.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936964AbeF3MDs (ORCPT ); Sat, 30 Jun 2018 08:03:48 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:37980 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936201AbeF3MDq (ORCPT ); Sat, 30 Jun 2018 08:03:46 -0400 Received: from localhost (unknown [183.108.164.149]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 945A0144C612D; Sat, 30 Jun 2018 05:03:44 -0700 (PDT) Date: Sat, 30 Jun 2018 21:03:42 +0900 (KST) Message-Id: <20180630.210342.804224843120744818.davem@davemloft.net> To: lipeng321@huawei.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com, yisen.zhuang@huawei.com, salil.mehta@huawei.com Subject: Re: [PATCH net-next 05/10] net: hns3: using modulo for cyclic counters in hclge_cmd_send From: David Miller In-Reply-To: <1530271385-49668-6-git-send-email-lipeng321@huawei.com> References: <1530271385-49668-1-git-send-email-lipeng321@huawei.com> <1530271385-49668-6-git-send-email-lipeng321@huawei.com> X-Mailer: Mew version 6.7 on Emacs 26 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Sat, 30 Jun 2018 05:03:46 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peng Li Date: Fri, 29 Jun 2018 19:23:00 +0800 > @@ -228,8 +228,7 @@ int hclge_cmd_send(struct hclge_hw *hw, struct hclge_desc *desc, int num) > desc_to_use = &hw->cmq.csq.desc[hw->cmq.csq.next_to_use]; > *desc_to_use = desc[handle]; > (hw->cmq.csq.next_to_use)++; > - if (hw->cmq.csq.next_to_use == hw->cmq.csq.desc_num) > - hw->cmq.csq.next_to_use = 0; > + hw->cmq.csq.next_to_use %= hw->cmq.csq.desc_num; > handle++; I would advise against this. The "%" modulus operation takes many cpu cycles, and the current code is thus much faster.