From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f45.google.com (mail-vk0-f45.google.com [209.85.213.45]) by dpdk.org (Postfix) with ESMTP id 8104458CB for ; Fri, 18 Sep 2015 12:33:37 +0200 (CEST) Received: by vkao3 with SMTP id o3so27320761vka.2 for ; Fri, 18 Sep 2015 03:33:37 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:date:message-id:subject:from:to :content-type; bh=RtWAJWG/pSD9pCC4CzzJU3Jcc1nTd/fnulkd2sxHlj8=; b=RZ0eoM2QjSulGDKeTUG+0cFmAnxJPeFv1z/oxQ9wevMS75pbCkO+TUmdrOQfH/jPOn fsbw5joBD+O/rF6WoV8RqZxP2QJ3dZkwi/qM+OfRPguJPLQql/v6fgoNQijKmyMup2d2 gs5thJjkHdsk5w5p3Xynyv5QP7jFeoraY+pB2opKOlOCAjFwL8yVcpd0w33zA2sP9RLM K5Yht29yRUGMVCR4epf4FVELNAXeFwL98GIKfrdwK8fjA32P26owx3K5uyGdvOfT1xxq hugFHtBzJP1PF+hct2PZ8PXdjiKXR9w36PvzXKk8mw804X5Adp+J4SfuagX9RcGSR66Z fBGQ== X-Gm-Message-State: ALoCoQm5RSdBVeWoL2A+73X7OyB6/QPS9sfZaEDVFaAAyQ2tEGiBu3Ro9TFaTjzEh4Gu2gzbeqFp MIME-Version: 1.0 X-Received: by 10.31.16.202 with SMTP id 71mr3049071vkq.125.1442572416789; Fri, 18 Sep 2015 03:33:36 -0700 (PDT) Received: by 10.103.48.86 with HTTP; Fri, 18 Sep 2015 03:33:36 -0700 (PDT) Date: Fri, 18 Sep 2015 11:33:36 +0100 Message-ID: From: Alejandro Lucero To: dev Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: [dpdk-dev] rte_eth_rx_queue_count accuracy X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 18 Sep 2015 10:33:37 -0000 I have seen the API definition says nothing about accuracy but some PMD implementations sacrifice accuracy for the sake of performance. If I'm not understanding the code wrongly i40e and ixgbe check DD bit just for the first descriptor in a group of 4, and they take all of them as used if the first descriptor is used. By other hand, they do a "heavy" calculation when the descriptor ring wraps which does not make sense (to me) if same performance goal is used. There are PMDs not supporting this option and I can not see any app or example using it so I do not know how important is this function, its accuracy and its performance impact. Can someone comment on this? Thanks