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[204.195.123.141]) by smtp.gmail.com with ESMTPSA id jb14-20020a170903258e00b001d077da4ac4sm3340846plb.212.2024.01.12.08.30.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jan 2024 08:30:44 -0800 (PST) Date: Fri, 12 Jan 2024 08:30:40 -0800 From: Stephen Hemminger To: Jerin Jacob Cc: jerinj@marvell.com, dev@dpdk.org, Thomas Monjalon , Ferruh Yigit , Andrew Rybchenko , ferruh.yigit@xilinx.com, ajit.khaparde@broadcom.com, aboyer@pensando.io, beilei.xing@intel.com, bruce.richardson@intel.com, chas3@att.com, chenbo.xia@intel.com, ciara.loftus@intel.com, dsinghrawat@marvell.com, ed.czeck@atomicrules.com, evgenys@amazon.com, grive@u256.net, g.singh@nxp.com, zhouguoyang@huawei.com, haiyue.wang@intel.com, hkalra@marvell.com, heinrich.kuhn@corigine.com, hemant.agrawal@nxp.com, hyonkim@cisco.com, igorch@amazon.com, irusskikh@marvell.com, jgrajcia@cisco.com, jasvinder.singh@intel.com, jianwang@trustnetic.com, jiawenwu@trustnetic.com, jingjing.wu@intel.com, johndale@cisco.com, john.miller@atomicrules.com, linville@tuxdriver.com, keith.wiles@intel.com, kirankumark@marvell.com, oulijun@huawei.com, lironh@marvell.com, longli@microsoft.com, mw@semihalf.com, spinler@cesnet.cz, matan@nvidia.com, matt.peters@windriver.com, maxime.coquelin@redhat.com, mk@semihalf.com, humin29@huawei.com, pnalla@marvell.com, ndabilpuram@marvell.com, qiming.yang@intel.com, qi.z.zhang@intel.com, radhac@marvell.com, rahul.lakkireddy@chelsio.com, rmody@marvell.com, rosen.xu@intel.com, sachin.saxena@oss.nxp.com, skoteshwar@marvell.com, shshaikh@marvell.com, shaibran@amazon.com, shepard.siegel@atomicrules.com, asomalap@amd.com, somnath.kotur@broadcom.com, sthemmin@microsoft.com, steven.webster@windriver.com, skori@marvell.com, mtetsuyah@gmail.com, vburru@marvell.com, viacheslavo@nvidia.com, xiao.w.wang@intel.com, cloud.wangxiaoyun@huawei.com, yisen.zhuang@huawei.com, yongwang@vmware.com, xuanziyang2@huawei.com, cristian.dumitrescu@intel.com Subject: Re: [dpdk-dev] [v1] ethdev: support Tx queue used count Message-ID: <20240112083040.69154f06@hermes.local> In-Reply-To: References: <20231219172948.3909749-1-jerinj@marvell.com> <20240111151745.3800170-1-jerinj@marvell.com> <20240111090011.664c8888@hermes.local> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Fri, 12 Jan 2024 12:31:27 +0530 Jerin Jacob wrote: > > > > Has anyone investigated implementing dynamic tx queue limits like > > Linux BQL? > > In DPDK APIs, it can expressed through creating correct TM > topology(shaping or rate limiting) via rte_tm API That won't work for BQL. Byte Queue Limits measures the latency for transmit queue. A counter is started when packets are queued to hardware and decremented when they are done transmitting. This is then fed back into the transmit logic; the concept is too eliminate bufferbloat in the transmit side by providing early feedback up the stack. Doing BQL needs a mechanism to know when packets are sent, either in ethdev or in every device driver. Right now it is common for applications to have very large worse case transmit queue length (descriptors) and that introduces latency.