From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f51.google.com (mail-pa0-f51.google.com [209.85.220.51]) by dpdk.org (Postfix) with ESMTP id 827795A86 for ; Thu, 1 Oct 2015 23:17:51 +0200 (CEST) Received: by pacfv12 with SMTP id fv12so87158179pac.2 for ; Thu, 01 Oct 2015 14:17:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:to:references:cc:from:message-id:date:user-agent :mime-version:in-reply-to:content-type:content-transfer-encoding; bh=IuFPZN2qPJ+JfKcHsCPX0A6Qh3MVjeSHlHOJMuKydBM=; b=U3XUWqlpMwA8dpsUl8xqZARmd3ui/S3qCjTFpVhpMQyLJ0YIRMW58+HG/n15wjfLUA ZinqfSwMV2+oIDvjp6n1n3MrnqQvXA0W3YILcpnhmibPiUcdGfJd0WjA2i+FM+fKout3 IT4wKVQaKY7FLG7nlAGndbRhUMsGCi2+41gz+a2De733annEJlth+UPK5I6QezuLF/bV ln6mKevvR6+0uijXrcHOpLdF+keDOjzXWkf+lICnK0y793Tg8yT/VgGpuVPmROilNXdJ CHBG2+wpy7VJw7lniEJolXiW9Q2KeQhRI7qqt5+a4Irr3vBSICZ7YBEjTpJlF5gkbsVa Pg+w== X-Received: by 10.66.97.73 with SMTP id dy9mr14961750pab.115.1443734270755; Thu, 01 Oct 2015 14:17:50 -0700 (PDT) Received: from [192.168.1.188] (static-50-53-21-5.bvtn.or.frontiernet.net. [50.53.21.5]) by smtp.googlemail.com with ESMTPSA id mk5sm8496779pab.44.2015.10.01.14.17.49 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 01 Oct 2015 14:17:50 -0700 (PDT) To: "Michael S. Tsirkin" , Avi Kivity References: <560BDE24.8000308@scylladb.com> <20150930165359-mutt-send-email-mst@redhat.com> <560BF782.4070308@scylladb.com> <20150930175848-mutt-send-email-mst@redhat.com> <560C0171.7080507@scylladb.com> <20150930204016.GA29975@redhat.com> <20151001113828-mutt-send-email-mst@redhat.com> <560CF44A.60102@scylladb.com> <20151001120027-mutt-send-email-mst@redhat.com> <560CFB66.5050904@scylladb.com> <20151001123335-mutt-send-email-mst@redhat.com> From: Alexander Duyck Message-ID: <560DA2FD.1050507@gmail.com> Date: Thu, 1 Oct 2015 14:17:49 -0700 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: <20151001123335-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] Having troubles binding an SR-IOV VF to uio_pci_generic on Amazon instance 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: Thu, 01 Oct 2015 21:17:51 -0000 On 10/01/2015 02:42 AM, Michael S. Tsirkin wrote: > On Thu, Oct 01, 2015 at 12:22:46PM +0300, Avi Kivity wrote: >> even when they are some users >> prefer to avoid the performance penalty. > I don't think there's a measureable penalty from passing through the > IOMMU, as long as mappings are mostly static (i.e. iommu=pt). I sure > never saw any numbers that show such. It depends on the IOMMU. I believe Intel had a performance penalty on all CPUs prior to Ivy Bridge. Since then things have improved to where they are comparable to bare metal. The graph on page 5 of https://networkbuilders.intel.com/docs/Network_Builders_RA_vBRAS_Final.pdf shows the penalty clear as day. Pretty much anything before Ivy Bridge w/ small packets is slowed to a crawl with an IOMMU enabled. - Alex