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 535A3A055A for ; Thu, 27 Feb 2020 11:15:05 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 62E1737AF; Thu, 27 Feb 2020 11:15:04 +0100 (CET) Received: from mail-vs1-f67.google.com (mail-vs1-f67.google.com [209.85.217.67]) by dpdk.org (Postfix) with ESMTP id BE9632C4F for ; Thu, 27 Feb 2020 11:15:02 +0100 (CET) Received: by mail-vs1-f67.google.com with SMTP id u26so1479617vsg.2 for ; Thu, 27 Feb 2020 02:15:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=4LQOLpvemo158u6yWq4r3T4xXwSPfepFfr8l9020suE=; b=NJ6riFvMCRcKB01jGG/diV8LeNJE6bONxW52d2nvqFT5ctASPZSAQWG7WafIgjKuLC bFJCv7AMXO/88qJFWEyhLwDnAHDaCNtPWiTo6RD0TSAowyhjfTIeY6A314Hr2IffleEh i7TE4JkYXJCIatWJF3PSYPUokI+OxF8fd8lBx/8q0bpbZQc2vvKZj0zhh//YhQRPpLXZ V8n4DLotDyo9oz/mQT7Z9kEvNta6s2jXK3uyV+OgLiZ6bA4cava57SpLD21nG2wKWcLE 4v9lYL6dIV4/jZeYzWG/FKtzqGqENx2/mCeTEyeLUP+KW6XFRCZkQAnTvkKw5DQPN1hn a/QA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=4LQOLpvemo158u6yWq4r3T4xXwSPfepFfr8l9020suE=; b=uQ7peiwdRFd8oTwYGBcSfMJEYOtkn+KMeQZnRo+SM1oldRwDrkbBBrA7vT9VzP2lge iFuDaayRzL/gVcFQkP/7tfkvvx+ARNhJgGf7STs8KqetAuwbJoVtaAdelN++aMy+eIK3 w5dKP2Htdx1V+LwyAJ1t3KsM6ZhkJGk52YiZn7vEAjhRUaJFNXJXy0Mgdq40nU3slM67 dBXKPGjuomO+KpkEPmIYeZzwug2lSsJJmWMifottN61DskrMG6w79NzwBk0DoE06g3ZB ptFAmNMJQkDyK51BavHvhjoqNgKNaWSqOASJDFq68edyQNy+w2YG8qK0fAajAWEqT7J1 JJ3w== X-Gm-Message-State: APjAAAWINrcOjzyjJ4SuDM+81rx6Y93BE5jdUt7dmG70nnLCKDeTPerI vQw9IH4uu85m0w+2PKbGQb764+TZ1jJCfGouKFA= X-Google-Smtp-Source: APXvYqy8a9YIvDzNQ0Quw/g1ikxUiYreeN/Yh9j+d9yZidqfq7KdjRjGOIPLTTBEOwYCtL4YmBX4gCRtyWohMy+MHhM= X-Received: by 2002:a67:e18a:: with SMTP id e10mr2154089vsl.57.1582798502041; Thu, 27 Feb 2020 02:15:02 -0800 (PST) MIME-Version: 1.0 References: <20200226072518.3496f5ee@hermes.lan> In-Reply-To: <20200226072518.3496f5ee@hermes.lan> From: Archit Pandey Date: Thu, 27 Feb 2020 15:44:50 +0530 Message-ID: To: Stephen Hemminger Cc: "Avinash ." , users@dpdk.org, Gokul Bargaje , "Mohit P. Tahiliani" Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: Re: [dpdk-users] DPDK Enqueue Pipeline 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: , Errors-To: users-bounces@dpdk.org Sender: "users" In that case, since the packets have been prefetched on enqueue, would it be necessary to prefetch the packets again upon dequeue? As an example, DPDK's QoS scheduler only prefetches on enqueue (using a packet pipeline to hide prefetch latency). On Wed, Feb 26, 2020 at 8:55 PM Stephen Hemminger < stephen@networkplumber.org> wrote: > On Wed, 26 Feb 2020 16:08:17 +0530 > "Avinash ." wrote: > > > Hi all, > > The DPDK QoS scheduler has a 4-stage pipeline for enqueuing the packets. > > This is used for hiding the latency of prefetching the data structures. > > Why is there no pipeline for dequeuing the packets? > > How does the dequeue function maintain the state of a packet? In other > > words, if I want to backtrace the packet that is dequeued to get the info > > of what was the traffic class and from which queue the packet was > dequeued. > > Is there any way to get this. > > > > Thanks, > > Avinash. > > Prefetching after receive burst is the responsibility of the application. > You can't prefetch until the data arrives, and the amount and policy > for prefetch depends on the timing of the application. > > There simple examples in DPDK and more complex in how FD.io VPP does it. > -- Archit Pandey Senior Year B.Tech. Department of Computer Science and Engineering National Institute of Technology Karnataka Surathkal, India