From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <vladz@cloudius-systems.com> Received: from mail-wi0-f180.google.com (mail-wi0-f180.google.com [209.85.212.180]) by dpdk.org (Postfix) with ESMTP id C23366787 for <dev@dpdk.org>; Tue, 27 Oct 2015 20:14:59 +0100 (CET) Received: by wicll6 with SMTP id ll6so174786862wic.1 for <dev@dpdk.org>; Tue, 27 Oct 2015 12:14:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudius-systems_com.20150623.gappssmtp.com; s=20150623; h=subject:to:references:cc:from:message-id:date:user-agent :mime-version:in-reply-to:content-type:content-transfer-encoding; bh=GMxJhCZjBFcdU58iC6NNAhN9Qxt1uRbjKtC1Rth5WYA=; b=xDQfKgAHuhdmdp/dShUubS3gDiOQRq6vwzkpjmZZpQSdNeZcoGON4q6Y17UbqvtDMw pA9zaLC7BygQ1AKxD3LWx8uUv5ByGqG4kXtrRDzXxZKZCi8XnmYNbhpFhgZbqBMtEw4z c7s9Idhstc8kVsdloRbeceBySonDuDRYtXCiD+ftX5VddLSZhBrLmJE3PmeOT5SGB0xu yQX9x64K+UVjZVIOITNFNJKI+WBig3Od5nZQsX5sa4PE/8/hVyMo4YY848WEBSiqUjrP 21k05rOjE7wJB21rJeiLLezKidCXegriARa8WrqyNJ0W5yJnEj9V/lUPxxgLPSUu+pAL Q1XA== 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=GMxJhCZjBFcdU58iC6NNAhN9Qxt1uRbjKtC1Rth5WYA=; b=KUuhPufnsvP56oFprF+rcyxuu81vRrAwycvgGvU+2kGGZJqE2BqW8hbSvTX5Sl9Bi+ Qps2PO5cNIT+bSa2CB4txxvX/yfcjJ5E1L1sF3Of1ShGyOuBIxbTfYjUG/rsKBS69tFy q657IpA/n4hELPxF+v8krYfjcsxlU4D6CFPpApam1WcfV31ukUkgpLDRPpNfeNH0mdZH avzr/RhvX9KEGWl6tkc6wj8rvivFt1yRDqtvFfH8Qc18fTo744QMq/OiAyhXEXTf+aQL oxJ88DBBwNySy62PTGZFZmL16Uq1srdNqXYzVffCaplm7jKDJ4Yybsdr7amb28CUiybi yGwg== X-Gm-Message-State: ALoCoQk0PcGO7zCMgob1gbojm68u5f35BeBusJh3zuNNGYtyvVqLPCE1UicD2KLHD5yJXBOFVjUD X-Received: by 10.180.8.163 with SMTP id s3mr17856575wia.70.1445973299586; Tue, 27 Oct 2015 12:14:59 -0700 (PDT) Received: from [10.0.0.2] (bzq-79-180-197-252.red.bezeqint.net. [79.180.197.252]) by smtp.googlemail.com with ESMTPSA id iw8sm46326540wjb.5.2015.10.27.12.14.58 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 27 Oct 2015 12:14:58 -0700 (PDT) To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>, Thomas Monjalon <thomas.monjalon@6wind.com>, "Zhang, Helin" <helin.zhang@intel.com> References: <1440085070-13989-1-git-send-email-vladz@cloudius-systems.com> <55DAD1C9.3010802@cloudius-systems.com> <1764015.lv7zT9MUyf@xps13> <562FC6D4.8000202@cloudius-systems.com> <2601191342CEEE43887BDE71AB97725836AB5A51@irsmsx105.ger.corp.intel.com> From: Vlad Zolotarov <vladz@cloudius-systems.com> Message-ID: <562FCD31.60508@cloudius-systems.com> Date: Tue, 27 Oct 2015 21:14:57 +0200 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: <2601191342CEEE43887BDE71AB97725836AB5A51@irsmsx105.ger.corp.intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: "dev@dpdk.org" <dev@dpdk.org>, "Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel.com>, "Brandeburg, Jesse" <jesse.brandeburg@intel.com> Subject: Re: [dpdk-dev] [PATCH v4] ixgbe_pmd: enforce RS bit on every EOP descriptor for devices newer than 82598 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK <dev.dpdk.org> List-Unsubscribe: <http://dpdk.org/ml/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://dpdk.org/ml/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <http://dpdk.org/ml/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Tue, 27 Oct 2015 19:14:59 -0000 On 10/27/15 21:10, Ananyev, Konstantin wrote: > Hi lads, > >> -----Original Message----- >> From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com] >> Sent: Tuesday, October 27, 2015 6:48 PM >> To: Thomas Monjalon; Ananyev, Konstantin; Zhang, Helin >> Cc: dev@dpdk.org; Kirsher, Jeffrey T; Brandeburg, Jesse >> Subject: Re: [dpdk-dev] [PATCH v4] ixgbe_pmd: enforce RS bit on every EOP descriptor for devices newer than 82598 >> >> >> >> On 10/27/15 20:09, Thomas Monjalon wrote: >>> Any Follow-up to this discussion? >>> Should we mark this patch as rejected? >> Hmmm... This patch fixes an obvious spec violation. Why would it be >> rejected? > No I don't think we can reject the patch: > There is a reproducible TX hang on ixgbe PMD on described conditions. > Though, as I explained here: > http://dpdk.org/ml/archives/dev/2015-September/023574.html > Vlad's patch would cause quite a big slowdown. > We are still in the process to get an answer from HW guys are there any > alternatives that will allow to fix the problem and avoid the slowdown. +1 > Konstantin > >>> 2015-08-24 11:11, Vlad Zolotarov: >>>> On 08/20/15 18:37, Vlad Zolotarov wrote: >>>>> According to 82599 and x540 HW specifications RS bit *must* be >>>>> set in the last descriptor of *every* packet. >>>>> >>>>> Before this patch there were 3 types of Tx callbacks that were setting >>>>> RS bit every tx_rs_thresh descriptors. This patch introduces a set of >>>>> new callbacks, one for each type mentioned above, that will set the RS >>>>> bit in every EOP descriptor. >>>>> >>>>> ixgbe_set_tx_function() will set the appropriate Tx callback according >>>>> to the device family. >>>> [+Jesse and Jeff] >>>> >>>> I've started to look at the i40e PMD and it has the same RS bit >>>> deferring logic >>>> as ixgbe PMD has (surprise, surprise!.. ;)). To recall, i40e PMD uses a >>>> descriptor write-back >>>> completion mode. >>>> >>>> From the HW Spec it's unclear if RS bit should be set on *every* descriptor >>>> with EOP bit. However I noticed that Linux driver, before it moved to >>>> HEAD write-back mode, was setting RS >>>> bit on every EOP descriptor. >>>> >>>> So, here is a question to Intel guys: could u, pls., clarify this point? >>>> >>>> Thanks in advance, >>>> vlad >>>