Cover Detail
Show a cover letter.
GET /api/covers/60733/?format=api
{ "id": 60733, "url": "http://patchwork.dpdk.org/api/covers/60733/?format=api", "web_url": "http://patchwork.dpdk.org/project/dpdk/cover/20191009133849.69002-1-yong.liu@intel.com/", "project": { "id": 1, "url": "http://patchwork.dpdk.org/api/projects/1/?format=api", "name": "DPDK", "link_name": "dpdk", "list_id": "dev.dpdk.org", "list_email": "dev@dpdk.org", "web_url": "http://core.dpdk.org", "scm_url": "git://dpdk.org/dpdk", "webscm_url": "http://git.dpdk.org/dpdk", "list_archive_url": "https://inbox.dpdk.org/dev", "list_archive_url_format": "https://inbox.dpdk.org/dev/{}", "commit_url_format": "" }, "msgid": "<20191009133849.69002-1-yong.liu@intel.com>", "list_archive_url": "https://inbox.dpdk.org/dev/20191009133849.69002-1-yong.liu@intel.com", "date": "2019-10-09T13:38:35", "name": "[v4,00/14] vhost packed ring performance optimization", "submitter": { "id": 17, "url": "http://patchwork.dpdk.org/api/people/17/?format=api", "name": "Marvin Liu", "email": "yong.liu@intel.com" }, "mbox": "http://patchwork.dpdk.org/project/dpdk/cover/20191009133849.69002-1-yong.liu@intel.com/mbox/", "series": [ { "id": 6753, "url": "http://patchwork.dpdk.org/api/series/6753/?format=api", "web_url": "http://patchwork.dpdk.org/project/dpdk/list/?series=6753", "date": "2019-10-09T13:38:35", "name": "vhost packed ring performance optimization", "version": 4, "mbox": "http://patchwork.dpdk.org/series/6753/mbox/" } ], "comments": "http://patchwork.dpdk.org/api/covers/60733/comments/", "headers": { "Return-Path": "<dev-bounces@dpdk.org>", "X-Original-To": "patchwork@dpdk.org", "Delivered-To": "patchwork@dpdk.org", "Received": [ "from [92.243.14.124] (localhost [127.0.0.1])\n\tby dpdk.org (Postfix) with ESMTP id 456021C042;\n\tWed, 9 Oct 2019 07:59:27 +0200 (CEST)", "from mga12.intel.com (mga12.intel.com [192.55.52.136])\n\tby dpdk.org (Postfix) with ESMTP id 951661C031\n\tfor <dev@dpdk.org>; Wed, 9 Oct 2019 07:59:25 +0200 (CEST)", "from fmsmga002.fm.intel.com ([10.253.24.26])\n\tby fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384;\n\t08 Oct 2019 22:59:25 -0700", "from npg-dpdk-virtual-marvin-dev.sh.intel.com ([10.67.119.142])\n\tby fmsmga002.fm.intel.com with ESMTP; 08 Oct 2019 22:59:22 -0700" ], "X-Amp-Result": "SKIPPED(no attachment in message)", "X-Amp-File-Uploaded": "False", "X-ExtLoop1": "1", "X-IronPort-AV": "E=Sophos;i=\"5.67,273,1566889200\"; d=\"scan'208\";a=\"223473359\"", "From": "Marvin Liu <yong.liu@intel.com>", "To": "maxime.coquelin@redhat.com, tiwei.bie@intel.com, zhihong.wang@intel.com, \n\tstephen@networkplumber.org, gavin.hu@arm.com", "Cc": "dev@dpdk.org,\n\tMarvin Liu <yong.liu@intel.com>", "Date": "Wed, 9 Oct 2019 21:38:35 +0800", "Message-Id": "<20191009133849.69002-1-yong.liu@intel.com>", "X-Mailer": "git-send-email 2.17.1", "In-Reply-To": "<20190925171329.63734-1-yong.liu@intel.com>", "References": "<20190925171329.63734-1-yong.liu@intel.com>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=UTF-8", "Content-Transfer-Encoding": "8bit", "Subject": "[dpdk-dev] [PATCH v4 00/14] vhost packed ring performance\n\toptimization", "X-BeenThere": "dev@dpdk.org", "X-Mailman-Version": "2.1.15", "Precedence": "list", "List-Id": "DPDK patches and discussions <dev.dpdk.org>", "List-Unsubscribe": "<https://mails.dpdk.org/options/dev>,\n\t<mailto:dev-request@dpdk.org?subject=unsubscribe>", "List-Archive": "<http://mails.dpdk.org/archives/dev/>", "List-Post": "<mailto:dev@dpdk.org>", "List-Help": "<mailto:dev-request@dpdk.org?subject=help>", "List-Subscribe": "<https://mails.dpdk.org/listinfo/dev>,\n\t<mailto:dev-request@dpdk.org?subject=subscribe>", "Errors-To": "dev-bounces@dpdk.org", "Sender": "\"dev\" <dev-bounces@dpdk.org>" }, "content": "Packed ring has more compact ring format and thus can significantly\nreduce the number of cache miss. It can lead to better performance.\nThis has been approved in virtio user driver, on normal E5 Xeon cpu\nsingle core performance can raise 12%.\n\nhttp://mails.dpdk.org/archives/dev/2018-April/095470.html\n\nHowever vhost performance with packed ring performance was decreased.\nThrough analysis, mostly extra cost was from the calculating of each\ndescriptor flag which depended on ring wrap counter. Moreover, both\nfrontend and backend need to write same descriptors which will cause\ncache contention. Especially when doing vhost enqueue function, virtio\nrefill packed ring function may write same cache line when vhost doing\nenqueue function. This kind of extra cache cost will reduce the benefit\nof reducing cache misses. \n\nFor optimizing vhost packed ring performance, vhost enqueue and dequeue\nfunction will be splitted into fast and normal path.\n\nSeveral methods will be taken in fast path:\n Handle descriptors in one cache line by batch.\n Split loop function into more pieces and unroll them.\n Prerequisite check that whether I/O space can copy directly into mbuf\n space and vice versa. \n Prerequisite check that whether descriptor mapping is successful.\n Distinguish vhost used ring update function by enqueue and dequeue\n function.\n Buffer dequeue used descriptors as many as possible.\n Update enqueue used descriptors by cache line.\n Disable sofware prefetch if hardware can do better.\n\nAfter all these methods done, single core vhost PvP performance with 64B\npacket on Xeon 8180 can boost 40%.\n\nv4:\n- Support meson build\n- Remove memory region cache for no clear performance gain and ABI break\n- Not assume ring size is power of two\n\nv3:\n- Check available index overflow\n- Remove dequeue remained descs number check\n- Remove changes in split ring datapath\n- Call memory write barriers once when updating used flags\n- Rename some functions and macros\n- Code style optimization\n\nv2:\n- Utilize compiler's pragma to unroll loop, distinguish clang/icc/gcc\n- Buffered dequeue used desc number changed to (RING_SZ - PKT_BURST)\n- Optimize dequeue used ring update when in_order negotiated\n\n\nMarvin Liu (14):\n vhost: add single packet enqueue function\n vhost: unify unroll pragma parameter\n vhost: add batch enqueue function for packed ring\n vhost: add single packet dequeue function\n vhost: add batch dequeue function\n vhost: flush vhost enqueue shadow ring by batch\n vhost: add flush function for batch enqueue\n vhost: buffer vhost dequeue shadow ring\n vhost: split enqueue and dequeue flush functions\n vhost: optimize enqueue function of packed ring\n vhost: add batch and single zero dequeue functions\n vhost: optimize dequeue function of packed ring\n vhost: check whether disable software pre-fetch\n vhost: optimize packed ring dequeue when in-order\n\n lib/librte_vhost/Makefile | 24 +\n lib/librte_vhost/meson.build | 11 +\n lib/librte_vhost/vhost.h | 33 ++\n lib/librte_vhost/virtio_net.c | 993 +++++++++++++++++++++++++++-------\n 4 files changed, 878 insertions(+), 183 deletions(-)" }