From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41720) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WuJyn-0000uy-IM for qemu-devel@nongnu.org; Tue, 10 Jun 2014 07:12:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WuJyb-0008VL-D7 for qemu-devel@nongnu.org; Tue, 10 Jun 2014 07:12:37 -0400 Received: from mail-wi0-x231.google.com ([2a00:1450:400c:c05::231]:53044) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WuJyb-0008VH-6C for qemu-devel@nongnu.org; Tue, 10 Jun 2014 07:12:25 -0400 Received: by mail-wi0-f177.google.com with SMTP id f8so5891925wiw.10 for ; Tue, 10 Jun 2014 04:12:24 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <5396E804.9090401@redhat.com> Date: Tue, 10 Jun 2014 13:12:04 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <988dc97c3b3e3c89066b3b3dc8c17b3fccc3c816.1402299637.git.hutao@cn.fujitsu.com> <20140609133246.286d749c@thinkpad> <20140610020021.GD29724@G08FNSTD100614.fnst.cn.fujitsu.com> <480968011.20454430.1402376972892.JavaMail.zimbra@redhat.com> <20140610083006.GA12425@G08FNSTD100614.fnst.cn.fujitsu.com> <5396C84A.8030202@redhat.com> <20140610095945.GH7423@redhat.com> In-Reply-To: <20140610095945.GH7423@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4 18/29] hostmem: add file-based HostMemoryBackend List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Yasunori Goto , Hu Tao , qemu-devel@nongnu.org, Eduardo Habkost , Igor Mammedov Il 10/06/2014 11:59, Michael S. Tsirkin ha scritto: > > >What's the point compared to memory-backend-ram? > > > > That you can use shared memory, for example together with vhost-user. > > I don't think it's a good idea until THP supports shared memory. Why? For example it would be useful for testing on machines that you don't have root for, and that do not have a hugetlbfs mount point. For example you could run the test case from the vhost-user's patches. THP is not a magic wand and you can get slowness from memory fragmentation at any time. We should not limit ourselves due to kernel bugs. Paolo