From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f195.google.com (mail-pl1-f195.google.com [209.85.214.195]) by dpdk.org (Postfix) with ESMTP id 52BED4C92 for ; Fri, 9 Nov 2018 19:47:03 +0100 (CET) Received: by mail-pl1-f195.google.com with SMTP id s5-v6so1308736plq.11 for ; Fri, 09 Nov 2018 10:47:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=gLWN0GGrVkkoUey/QnEnDXnPksQLXp9E/3zlPUgzed0=; b=wRqQjMoJM7nIrseB2WgX9r2dtPdAnvMrZUgxHuCPKiV14KltKpVPrOyH1kgw6MUxdL x4WsEpsqCPxpfjXsAJR8tVuCAgQaAVOT5KwEfjbpaMkEbCErlFwUbDinemUs+4FTOv+u 4OXzT4NekjiPbyDHe7mDMmMaIK22ZvezvC7g4xcVILPn1D3PBZRweuNvT41yE5nodzXg ZfDE3wedD1JDusVKvPQ1KyAbNoArl7NqtvtCsX6KmWvrSsNA+0d+7b/WE97q4/Zwpw3i S0ET4Diy87tqlDKSr1ttBMom1AzkwlUDsL8uVSZbYyqeK/tKtwlB6dt9Y/b0246BZbwr +XvQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=gLWN0GGrVkkoUey/QnEnDXnPksQLXp9E/3zlPUgzed0=; b=oRIVEn4CnCAW5OBGO/wVArAEdDA6AJ9QLTuY8NuFOhISaqhgjXj86/gSP2l1wtHUsn QIk8SxXXBlNx3s/5ppOM3O2e6wbB3p/EFj40bP3f9HvrVlGL4U3lHNBThMoYvKuJTwuc yQakZ97gFfY/3vg44fcSgCZXtetO3bq0RXZTpYeJz0zDIcsE2Jty7rsrnBd918lErtXj Jy1jujuUgmeX5FKovDN9M5j6IOfOKXH2jYhhhDPie4+FsFrNm3+PsMI6NTH/qoOJgxKe TpzGVmwNJrDwjXaUpD1ycigePNx8CA8RVfdI1+RgHMPqkb412sEvyZnMpG24UmvEekl/ 5YPQ== X-Gm-Message-State: AGRZ1gL1tD/NQk7gF7krTZMi8zRq2WsRoviSFfXGhYyO3BFS+oSa64h5 QdwkKlAdtUlf0Nf90GN1a0UKyA== X-Google-Smtp-Source: AJdET5cTrbfWSofsJ97oW75sUfibdTdBQjZP9ETwvhNZNDD9S0H/S97Oxq8SQRZteFmLQgh4wyuT2g== X-Received: by 2002:a17:902:544:: with SMTP id 62-v6mr9518546plf.73.1541789222182; Fri, 09 Nov 2018 10:47:02 -0800 (PST) Received: from xeon-e3 (204-195-22-127.wavecable.com. [204.195.22.127]) by smtp.gmail.com with ESMTPSA id o7-v6sm11149245pfb.23.2018.11.09.10.47.01 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 09 Nov 2018 10:47:02 -0800 (PST) Date: Fri, 9 Nov 2018 10:46:54 -0800 From: Stephen Hemminger To: Thomas Monjalon Cc: keith.wiles@intel.com, Yongseok Koh , ferruh.yigit@intel.com, dev@dpdk.org, bruce.richardson@intel.com, Shahaf Shuler , konstantin.ananyev@intel.com, anatoly.burakov@intel.com, stable@dpdk.org, justin.parus@microsoft.com, christian.ehrhardt@canonical.com, david.coronel@canonical.com, josh.powers@canonical.com, jay.vosburgh@canonical.com, dan.streetman@canonical.com Message-ID: <20181109104654.795db38a@xeon-e3> In-Reply-To: <1612642.At0RDolh7h@xps> References: <20181023212318.43082-1-yskoh@mellanox.com> <432F92CE-5714-45DC-B72F-CD8771DAFC89@intel.com> <1612642.At0RDolh7h@xps> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-stable] [dpdk-dev] AVX512 bug on SkyLake X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Nov 2018 18:47:03 -0000 On Thu, 08 Nov 2018 16:59:22 +0100 Thomas Monjalon wrote: > Hi, > > We need to gather more information about this bug. > More below. > > 07/11/2018 10:04, Wiles, Keith: > > > On Nov 6, 2018, at 9:30 PM, Yongseok Koh wrote: > > >> On Nov 5, 2018, at 6:06 AM, Wiles, Keith wrote: > > >>> On Nov 2, 2018, at 9:04 PM, Yongseok Koh wrote: > > >>> > > >>> This is a workaround to prevent a crash, which might be caused by > > >>> optimization of newer gcc (7.3.0) on Intel Skylake. > > >> > > >> Should the code below not also test for the gcc version and > > >> the Sky Lake processor, maybe I am wrong but it seems it is > > >> turning AVX512 for all GCC builds > > > > > > I didn't want to check gcc version as 7.3.0 is very new. Only gcc 8 is newly up since then (gcc 8.2). > > > Also, I wasn't able to test every gcc versions and I wanted to be a bit conservative for this crash. > > > Performance drop (if any) by disabling a new (experimental) feature would be less risky than unaccountable crash. > > > And, it does disable the feature only if CONFIG_RTE_ENABLE_AVX512=n. Please refer to v3. > > > > Are you not turning off all of the GCC versions for AVX512. > > And you can test for range or greater then GCC version and > > it just seems like we are turning off every gcc version, is that true? > > Do we know exactly which GCC versions are affected? > > > >> Also bug 97 seems a bit obscure reference, maybe you know > > >> the bug report, but more details would be good? > > > > > > I sent out the report to dev list two month ago. > > > And I created the Bug 97 in order to reference it > > > in the commit message. > > > I didn't want to repeat same message here and there, > > > but it would've been better to have some sort of summary > > > of the Bug, although v3 has a few more words. > > > However, v3 has been merged. > > > > Still this is too obscure if nothing else give a link to > > a specific bug not just 97. > > The URL is > https://bugs.dpdk.org/show_bug.cgi?id=97 > The bug is also pointing to an email: > https://mails.dpdk.org/archives/dev/2018-September/111522.html > > Summary: > - CPU: Intel Skylake > - Linux environment: Ubuntu 18.04 > - Compiler: gcc-7.3 (Ubuntu 7.3.0-16ubuntu3) > - Scenario: testpmd crashes when it starts forwarding > - Behaviour: AVX2 version of rte_memcpy() optimized with 512b instructions > - Fix: disable AVX512 optimization with -mno-avx512f > > It seems to have been reproduced only when using mlx5 PMD so far. > Any other experience? > > I did a little checking, there are only a few machine types on Azure that are Skylake. These are obviously the high end lateset ones... https://azure.microsoft.com/en-us/blog/fv2-vms-are-now-available-the-fastest-vms-on-azure/