From mboxrd@z Thu Jan 1 00:00:00 1970 From: "lipeng (Y)" Subject: Re: [PATCH net-next 05/10] net: hns3: using modulo for cyclic counters in hclge_cmd_send Date: Mon, 2 Jul 2018 15:06:46 +0800 Message-ID: <5ef0b797-67ff-e84a-367d-bd3da96a13b3@huawei.com> References: <1530271385-49668-1-git-send-email-lipeng321@huawei.com> <1530271385-49668-6-git-send-email-lipeng321@huawei.com> <20180630.210342.804224843120744818.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Cc: , , , , To: David Miller Return-path: In-Reply-To: <20180630.210342.804224843120744818.davem@davemloft.net> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 2018/6/30 20:03, David Miller wrote: > 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. > > . Agree with you. Thanks for your review, we  concentrate on  the code style and ignore the performance in this patch, It is not good. I will remove this patch from the patchset. >