From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f170.google.com (mail-wr0-f170.google.com [209.85.128.170]) by dpdk.org (Postfix) with ESMTP id 7B59B2BB9 for ; Fri, 9 Jun 2017 13:19:24 +0200 (CEST) Received: by mail-wr0-f170.google.com with SMTP id v104so29435666wrb.0 for ; Fri, 09 Jun 2017 04:19:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=atomicrules-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=ukpZ+d3IhVcvq23lxOw2WGpB5jNFHAvWOgjRxvq7uNk=; b=P3VA+j55rZC7eCBT1zCBMummjBTMi5XOsAkFf9aU6ti3W4gUA5uo+1WEFFAAyQbK1x Tph9arSwsCpAJePRQ4VQp70XsHKICqRtRESSYAdnhiEkmOWhD3vDx8wjfFVHtPMqgohp FGmlIefKHFxwrX0DPcBoSSNkB+yYygojDCVbIxkMl8s7+STBwODJ3SojQ1CuOyFKzb/m jS7eE5A9NrFKuPeP4vqwwbvKyvFuGMHq/J4hGaibECT7TTgwSQZyIHgtpc/LC9GcYxt9 /l1gh56EmIkCm7JM76o+QcsRDm3nG97wMSc1mv4VEmCPoJchkyuI/wLZ+FYpYnCfYJh9 HZvQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=ukpZ+d3IhVcvq23lxOw2WGpB5jNFHAvWOgjRxvq7uNk=; b=mK7mDjjc8oi/gz0eO8IAo6eesHaQ0+arZwmVvsW9kjqaBuW7P59Y14RBE9mtG8LA33 jk/XaMcJBAK0pdErwXVU/KcEfpfUwGHls6k7qssOduDLb/13Jvlt8uOvgBUqS5dgp+al IY9aP606ZhWUirQbU+YFOVSM/SXZA/BNBSdPV2S4H+5RmHM2qenzuy15F0Q0nKee2g3D jKZEm9CvllTDHF2DZhbbnW8e8QIXTeLX9Leq0Eh5EIIqVGooS/8SzgOvo0M9QJ0SonfF 2WV1lhLaa2lJzWOogIdaPA0PSMlQKL6QQqDYRATjzkl5A7yrfPYOmoh0JPulWbD4i7pq P5TQ== X-Gm-Message-State: AODbwcBPPDesz0FKP5MLdyujUCRIoFyvwKBDdAdivH/klexidsIZniiq Wtaz6J23uEuuqlPEJsGimK3bvk/Uq9WT X-Received: by 10.223.173.137 with SMTP id w9mr25519962wrc.49.1497007164116; Fri, 09 Jun 2017 04:19:24 -0700 (PDT) MIME-Version: 1.0 Received: by 10.28.113.91 with HTTP; Fri, 9 Jun 2017 04:19:22 -0700 (PDT) In-Reply-To: References: <20170608102514.2e5a1097@xeon-e3> From: Shepard Siegel Date: Fri, 9 Jun 2017 07:19:22 -0400 Message-ID: To: Vijay Cc: Stephen Hemminger , users@dpdk.org Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: Re: [dpdk-users] Packet spacing in DPDK X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Jun 2017 11:19:24 -0000 Even though DPDK sends packets down to the hardware as fast as possible, which is a great thing; it can also send down useful metadata. Some merchant NIC ASICs have hardware to support egress pacing, which their DPDK PMDs may or may not expose. Last year with our FPGA-based Arkville product, we developed a prototype "Paced Packet Player" which used TX/egress packet metadata to determine each individual packet's release to the MAC TX port, packet-by-packet. To ns precision. On four parallel 100 GbE ports. I blogged about it here. http://atomicrules.blogspot.co.uk/2017/01/paced-packet-player.html The point is, that depending on your ability to add some dedicated logic just ahead of the TX MAC; DPDK's TX metadata can be used to provide egress packet-pacing to hardware. If or not your particular NIC can use this data is a function of your NIC hardware and the associated PMD. -Shep On Thu, Jun 8, 2017 at 1:51 PM, Vijay wrote: > So, for example, at every 1 Sec interval if 1000 packets need to > transmitted, then HW tries to send them as fast as possible ? Is there any > document which talks about this ? > > On Thu, Jun 8, 2017 at 10:25 AM, Stephen Hemminger < > stephen@networkplumber.org> wrote: > > > On Thu, 8 Jun 2017 09:50:05 -0700 > > Vijay wrote: > > > > > Hi, > > > > > > I am new to this mailing list and new to DPDK. I would like to know > about > > > packet spacing when a burst of packets are being transmitted. For > > example: > > > there is a timer running and at expiry of the timer there could > multiple > > > frames that need to transmitted. So, will these frames be spaced by > dpdk > > > before transmission ? Is it internally handled by dpdk ? Is there any > doc > > > that talks about this ? > > > > > > I am not sure if this question has already been asked. If yes, please > > point > > > me to the appropriate thread which talks about this. > > > > > > Thanks, > > > Vijay > > > > The packets in DPDK are not paced. The hardware sends them as fast as > > possible. > > >