From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f181.google.com (mail-wi0-f181.google.com [209.85.212.181]) by dpdk.org (Postfix) with ESMTP id 050128D91 for ; Thu, 1 Oct 2015 11:53:17 +0200 (CEST) Received: by wicge5 with SMTP id ge5so21341224wic.0 for ; Thu, 01 Oct 2015 02:53:16 -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=5Wf/jdNd9yXkQMa4mLxSaXDO4kUxorRfQGJLKuuqamc=; b=P5WyU37Ww09f9lkECilqLhIOdvGkf1bkwsKN0H6i9d92TMljrKHn/1zMvN/bobXw7Z qQNHvx31zz02NqF4lq9ZrSbpUK95JgsMLC8afabriX0BVZGc7FTXyBRfwq1kFA6N9r1X 4IayqE4VfUQFpRwl2LGxOXAVTwf6jzpCrOzHOnHC0J+ISP+5bVkE0VE2M3IYs4eKuQg1 7wdtpO49WS1DAkBDCIiLrfY9R5Pm3te/VXxOr1rR3BugVQcV98M7SJujG0+VoG5x+eLc fJ2fpRoGJwQAnv6zHq+NX9QQwHTv53FjUPLniR6Aat4bNXRwaDjcRoznE5VdnjBV28nn xlGg== X-Gm-Message-State: ALoCoQnIX5oQapAAqd5vcYxaWVG1C8M15GS+HE3etSSkecujito4Pl5ZwrDZvdi1sgaDX+J87Vvh X-Received: by 10.180.211.243 with SMTP id nf19mr2388673wic.74.1443693196801; Thu, 01 Oct 2015 02:53:16 -0700 (PDT) Received: from avi.cloudius ([37.142.229.250]) by smtp.googlemail.com with ESMTPSA id s2sm2298293wib.15.2015.10.01.02.53.15 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 Oct 2015 02:53:15 -0700 (PDT) To: "Michael S. Tsirkin" 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: Avi Kivity Message-ID: <560D028A.8050509@scylladb.com> Date: Thu, 1 Oct 2015 12:53:14 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 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 09:53:17 -0000 On 10/01/2015 12:42 PM, 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. > Maybe not. But again, virtualized setups will not have a guest iommu and therefore can't use it; and those happen to be exactly the setups you're blocking. Non-virtualized setups have an iommu available, but they can also use pci_uio_generic without patching if they like. The virtualized setups have no other option; you're leaving them out in the cold.