From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f176.google.com (mail-wi0-f176.google.com [209.85.212.176]) by dpdk.org (Postfix) with ESMTP id 16C0A568C for ; Tue, 1 Sep 2015 16:50:19 +0200 (CEST) Received: by wiclp12 with SMTP id lp12so33634598wic.1 for ; Tue, 01 Sep 2015 07:50:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-type :content-transfer-encoding; bh=pOEvw/e9OA6+gS/iLgWti4L2XWtkOTabJkKmtyJHE6k=; b=kHHeRouAY4HjOJwSA2PMJ5z71eBfyBPwMAmZ5cNig3WnYgGrcfMGPE1Co++VBXFAoy Grtfkrjv5Lfpx/T/d7xvB2lb6H8CS7C0ZaI/K6WrZaH4hNbmlVCeHgtK8t8i2fVOlEeJ NAsUmUpDmfIO9LZlSjd3TMzy/Z/4bOEsz3CWzZWv9iVdggFlqC5/HCkmoSaQenfNB+Qr xvv4nY4KGsIQMygqsU/TwzKMfYADljggI0EUTtaGVN3OowhmCy8BOIucKWOkJj085Bq1 i69N5yqFfVStMO14isfsL7LGvSZzUFc+ln++S0yPUSCaOIt8MbFtJyZ3fMxIrMOHs65p MZiQ== X-Gm-Message-State: ALoCoQlehg4lX8BLj/EZr7DZhggkbmUo86gJE6jfCTgt72eWvjIpOUiLv6ZYl0X8hCl+z05ZY0LQ X-Received: by 10.194.78.230 with SMTP id e6mr34445371wjx.43.1441119018815; Tue, 01 Sep 2015 07:50:18 -0700 (PDT) Received: from avi.cloudius ([37.142.229.250]) by smtp.googlemail.com with ESMTPSA id fn8sm3134822wib.2.2015.09.01.07.50.17 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 01 Sep 2015 07:50:17 -0700 (PDT) To: Matthew Hall , =?UTF-8?Q?Martin_Dra=c5=a1ar?= References: <55E44563.5050208@ics.muni.cz> <55E5B81E.8010601@ics.muni.cz> <20150901144726.GA30421@mhcomputing.net> From: Avi Kivity Message-ID: <55E5BB28.1090009@cloudius-systems.com> Date: Tue, 1 Sep 2015 17:50:16 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <20150901144726.GA30421@mhcomputing.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: dev@dpdk.org Subject: Re: [dpdk-dev] Broken RSS hash computation on Intel 82574L 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: Tue, 01 Sep 2015 14:50:19 -0000 On 09/01/2015 05:47 PM, Matthew Hall wrote: > On Tue, Sep 01, 2015 at 04:37:18PM +0200, Martin DraĊĦar wrote: >> Dne 1.9.2015 v 15:45 De Lara Guarch, Pablo napsal(a): >>> 82574L NIC uses em PMD, which does not support more than 1 queue. >>> Therefore RSS is disabled in the NIC and then you cannot have RSS hashes. >>> >>> Thanks, >>> Pablo >> Hi Pablo, >> >> that is an interesting information. I read the rationale in em_ethdev.c >> and I was wondering, what would have to be done to enable RSS hash >> computation on that card. I can live with just one RX queue, but hashes >> would help me a lot. The computer which is using those NICs is not that >> powerful and every bit of offloaded computation counts... >> >> Thanks, >> Martin > RSS calculations are used to direct packets across multiple RX queues. With > only one RX queue it cannot possibly increase performance by enabling it. > As an example, seastar uses the RSS hash computed by the NIC to select a core to process on, if the number of hardware queues is smaller than the number of cores.