From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f44.google.com (mail-vk0-f44.google.com [209.85.213.44]) by dpdk.org (Postfix) with ESMTP id 3EB9E282 for ; Thu, 15 Dec 2016 20:29:41 +0100 (CET) Received: by mail-vk0-f44.google.com with SMTP id 137so77684159vkl.0 for ; Thu, 15 Dec 2016 11:29:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=a3ol5x2HFeYeCRNHyLstVTOGileSHfus1tbvIdEnEJs=; b=RxXDLBOKNEunTXMiNcM7MamZ42WL5Osrz51PXPs6JrX7q+WRf59gjnwahm9VK1Z7nZ ncpSMUjX39wkftYVN862Hy0F0QgKpU2yGniKHNZBvmF504Ct1ODIRt1fHVaNMBImDclR GwdixU/+ITUTykUYfaOzYbaUZuDhIvQ7dHtkkygdJr3cOLMWLzlM02wjh7y8Id9ugCOI oz3CxRGlqmYqMpAHBXEk23ZzKsD0F6jDTiWYFUtzgmZ8D5QEpXf5j/g1iakP2tBKtxU8 LTwsUkqNMcdA2oNAdCEkITVNkXYTvQDmU1How4XJBxV44i1m2uclVFVqAH28fdkCAQNx 6Waw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=a3ol5x2HFeYeCRNHyLstVTOGileSHfus1tbvIdEnEJs=; b=lL7mZmKBE+uo6pN2+h1ITs4jdk73JwZE9fvWQAEKUVjfvB/dleqcRHNvoUxzXoyErU idZhlY4siMNb9boi0+f2/YqgZKW728459zJmKz9A9oxGlShd6CDUrXPj0AlXGoLHbyFL ilFPgETLsokIjR4ShbAY9FEtZqsai6O6fh33kVECoaVuRwHxoaOr0WrNBO+/QbSCvUXt ccEb0CclsEI4i3k/pmvv2sMITWDzhAvlX/ZonHFBSGIcFDccu77HgETtALFFeNNg6EUl ec6P0iRejuJ8xXb5BvLRI/tauKE9Y29GBahEzYnl5/h+iTvR6klHNNiGnj2MH5HyM3KR PsDg== X-Gm-Message-State: AKaTC03f5nMs2oNmMw2pUxWoKDTIyLntkBI0qcls+6bVYN5aO3IMvWeArQSwhbPVY2kDB4xjFTiZqdJ4ZfrtcXGH X-Received: by 10.31.228.71 with SMTP id b68mr2729752vkh.163.1481830180701; Thu, 15 Dec 2016 11:29:40 -0800 (PST) MIME-Version: 1.0 Received: by 10.176.80.29 with HTTP; Thu, 15 Dec 2016 11:29:40 -0800 (PST) In-Reply-To: <20161215111427.3e9e72a2@xeon-e3> References: <88A92D351643BA4CB23E30315517062662F3C939@SHSMSX103.ccr.corp.intel.com> <20161215091740.0d34defe@xeon-e3> <20161215111427.3e9e72a2@xeon-e3> From: Jes Nielsen Date: Thu, 15 Dec 2016 13:29:40 -0600 Message-ID: To: Stephen Hemminger Cc: edgar helmut , "Hu, Xuekun" , "Wiles, Keith" , "users@dpdk.org" Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: Re: [dpdk-users] Dpdk poor performance on virtual machine X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Dec 2016 19:29:41 -0000 Are you perhaps running on an old Sandy Bridge x86? I heard that Intel Sandy Bridge CPUs have a limitation with their VT-d IOTLB that limits PCIe passthrough throughput. Sandy Bridge (and earlier) CPUs are not recommended if high performance is required. On Thu, Dec 15, 2016 at 1:14 PM, Stephen Hemminger < stephen@networkplumber.org> wrote: > On Thu, 15 Dec 2016 19:29:54 +0200 > edgar helmut wrote: > > > Stephen, this is not the case, it relies on using the transparent > hugepages > > which looks like 2M hugepages size. > > Why should be a problem to back 1G pages of the guest to 2M pages at the > > host? > > the transparent hugepages makes the deployment much more flexible. > > > The IOMMU has a cache (like TLB) which has a limited number of slots. > If using 2M pages then the IOMMU cache misses will cause a performance drop > just like CPU cache misses. I think Intel had some slides back at IDF 2012 > that showed the impact. > > -- Best Regards, Jes Nielsen 6WIND, Solutions Engineering Austin, TX 78730, USA Tel: (512) 426-8222 www.6wind.com This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and contains information that is confidential and proprietary to 6WIND. All unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.