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 D6F7EA3168 for ; Thu, 17 Oct 2019 09:31:30 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 7A1D61E4EB; Thu, 17 Oct 2019 09:31:30 +0200 (CEST) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 113151BFF9 for ; Thu, 17 Oct 2019 09:31:29 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 484D289B001; Thu, 17 Oct 2019 07:31:28 +0000 (UTC) Received: from [10.36.112.44] (ovpn-112-44.ams2.redhat.com [10.36.112.44]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 263985D9D5; Thu, 17 Oct 2019 07:31:25 +0000 (UTC) To: Marvin Liu , tiwei.bie@intel.com, zhihong.wang@intel.com, stephen@networkplumber.org, gavin.hu@arm.com Cc: dev@dpdk.org References: <20191015143014.1656-1-yong.liu@intel.com> <20191015160739.51940-1-yong.liu@intel.com> From: Maxime Coquelin Autocrypt: addr=maxime.coquelin@redhat.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0 MIME-Version: 1.0 In-Reply-To: <20191015160739.51940-1-yong.liu@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.67]); Thu, 17 Oct 2019 07:31:28 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH v6 00/13] vhost packed ring performance optimization 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" Hi Marvin, This is almost good, just fix the small comments I made. Also, please rebase on top of next-virtio branch, because I applied below patch from Flavio that you need to take into account: http://patches.dpdk.org/patch/61284/ Regards, Maxime On 10/15/19 6:07 PM, Marvin Liu wrote: > Packed ring has more compact ring format and thus can significantly > reduce the number of cache miss. It can lead to better performance. > This has been approved in virtio user driver, on normal E5 Xeon cpu > single core performance can raise 12%. > > http://mails.dpdk.org/archives/dev/2018-April/095470.html > > However vhost performance with packed ring performance was decreased. > Through analysis, mostly extra cost was from the calculating of each > descriptor flag which depended on ring wrap counter. Moreover, both > frontend and backend need to write same descriptors which will cause > cache contention. Especially when doing vhost enqueue function, virtio > refill packed ring function may write same cache line when vhost doing > enqueue function. This kind of extra cache cost will reduce the benefit > of reducing cache misses. > > For optimizing vhost packed ring performance, vhost enqueue and dequeue > function will be splitted into fast and normal path. > > Several methods will be taken in fast path: > Handle descriptors in one cache line by batch. > Split loop function into more pieces and unroll them. > Prerequisite check that whether I/O space can copy directly into mbuf > space and vice versa. > Prerequisite check that whether descriptor mapping is successful. > Distinguish vhost used ring update function by enqueue and dequeue > function. > Buffer dequeue used descriptors as many as possible. > Update enqueue used descriptors by cache line. > > After all these methods done, single core vhost PvP performance with 64B > packet on Xeon 8180 can boost 35%. > > v6: > - Fix dequeue zcopy result check > > v5: > - Remove disable sw prefetch as performance impact is small > - Change unroll pragma macro format > - Rename shadow counter elements names > - Clean dequeue update check condition > - Add inline functions replace of duplicated code > - Unify code style > > v4: > - Support meson build > - Remove memory region cache for no clear performance gain and ABI break > - Not assume ring size is power of two > > v3: > - Check available index overflow > - Remove dequeue remained descs number check > - Remove changes in split ring datapath > - Call memory write barriers once when updating used flags > - Rename some functions and macros > - Code style optimization > > v2: > - Utilize compiler's pragma to unroll loop, distinguish clang/icc/gcc > - Buffered dequeue used desc number changed to (RING_SZ - PKT_BURST) > - Optimize dequeue used ring update when in_order negotiated > > > Marvin Liu (13): > vhost: add packed ring indexes increasing function > vhost: add packed ring single enqueue > vhost: try to unroll for each loop > vhost: add packed ring batch enqueue > vhost: add packed ring single dequeue > vhost: add packed ring batch dequeue > vhost: flush enqueue updates by batch > vhost: flush batched enqueue descs directly > vhost: buffer packed ring dequeue updates > vhost: optimize packed ring enqueue > vhost: add packed ring zcopy batch and single dequeue > vhost: optimize packed ring dequeue > vhost: optimize packed ring dequeue when in-order > > lib/librte_vhost/Makefile | 18 + > lib/librte_vhost/meson.build | 7 + > lib/librte_vhost/vhost.h | 57 +++ > lib/librte_vhost/virtio_net.c | 924 +++++++++++++++++++++++++++------- > 4 files changed, 812 insertions(+), 194 deletions(-) >