From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id A59F8A00E6 for ; Thu, 11 Jul 2019 06:11:24 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 78FE83772; Thu, 11 Jul 2019 06:11:24 +0200 (CEST) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 63ACF2BAB for ; Thu, 11 Jul 2019 06:11:23 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C9E9B308C1E6; Thu, 11 Jul 2019 04:11:22 +0000 (UTC) Received: from [10.72.12.56] (ovpn-12-56.pek2.redhat.com [10.72.12.56]) by smtp.corp.redhat.com (Postfix) with ESMTP id DCF968081; Thu, 11 Jul 2019 04:11:18 +0000 (UTC) To: "Liu, Yong" , "Bie, Tiwei" , "maxime.coquelin@redhat.com" , "dev@dpdk.org" References: <20190708171320.38802-1-yong.liu@intel.com> <20190708171320.38802-3-yong.liu@intel.com> <86228AFD5BCD8E4EBFD2B90117B5E81E63334CE6@SHSMSX103.ccr.corp.intel.com> From: Jason Wang Message-ID: <435a2d7c-4751-95e7-73d7-9e519a3a893a@redhat.com> Date: Thu, 11 Jul 2019 12:11:17 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <86228AFD5BCD8E4EBFD2B90117B5E81E63334CE6@SHSMSX103.ccr.corp.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Thu, 11 Jul 2019 04:11:22 +0000 (UTC) Subject: Re: [dpdk-dev] [RFC PATCH 02/13] add vhost packed ring fast enqueue function X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 2019/7/10 下午3:30, Liu, Yong wrote: > >> -----Original Message----- >> From: Jason Wang [mailto:jasowang@redhat.com] >> Sent: Wednesday, July 10, 2019 12:28 PM >> To: Liu, Yong ; Bie, Tiwei ; >> maxime.coquelin@redhat.com; dev@dpdk.org >> Subject: Re: [dpdk-dev] [RFC PATCH 02/13] add vhost packed ring fast enqueue >> function >> >> >> On 2019/7/9 上午1:13, Marvin Liu wrote: >>> In fast enqueue function, will first check whether descriptors are >>> cache aligned. Fast enqueue function will check prerequisites in the >>> beginning. Fast enqueue function do not support chained mbufs, normal >>> function will handle that. >>> >>> Signed-off-by: Marvin Liu >> Any reason for not letting compiler to unroll the loops? >> > Hi Jason, > I'm not sure about how much compiler can help on unrolling loops as it can't know how much loops will create in one call. > After force not using unroll-loop optimization by "-fno-unroll-loops", virtio_dev_rx_packed function size remained the same. > So look like gcc unroll-loop optimization do not help here. I meant something like "pragma GCC unroll N" just before the loop you want unrolled. Thanks > > And fast enqueue function not only did unroll loop, it also checked cache alignment which can help performance in another side. > > Regards, > Marvin > >> Thanks >>