From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=59718 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OGwyj-000297-N7 for qemu-devel@nongnu.org; Tue, 25 May 2010 12:27:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OGwyi-0005xY-I2 for qemu-devel@nongnu.org; Tue, 25 May 2010 12:27:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:5211) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OGwyi-0005xG-B5 for qemu-devel@nongnu.org; Tue, 25 May 2010 12:27:40 -0400 Message-ID: <4BFBFA6B.7080501@redhat.com> Date: Tue, 25 May 2010 19:27:23 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm References: <20100519192222.GD61706@ncolin.muc.de> <4BF5A9D2.5080609@codemonkey.ws> <4BF91937.2070801@redhat.com> <4BFBAE46.5050801@redhat.com> <4BFBB3C1.9020905@redhat.com> <4BFBCFAC.9070807@codemonkey.ws> <4BFBD13C.60605@redhat.com> <4BFBD20E.5060207@codemonkey.ws> <4BFBD2D5.2000201@redhat.com> <4BFBD6CD.3000503@codemonkey.ws> <4BFBD82F.3020404@redhat.com> <4BFBD943.8020704@codemonkey.ws> <4BFBE614.9080306@redhat.com> <4BFBE64F.6020901@codemonkey.ws> <4BFBF7D4.80900@redhat.com> <4BFBF905.1030901@codemonkey.ws> In-Reply-To: <4BFBF905.1030901@codemonkey.ws> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Kevin Wolf , kvm@vger.kernel.org, qemu-devel@nongnu.org, Blue Swirl , ceph-devel@vger.kernel.org, Christian Brunner On 05/25/2010 07:21 PM, Anthony Liguori wrote: > On 05/25/2010 11:16 AM, Avi Kivity wrote: >> On 05/25/2010 06:01 PM, Anthony Liguori wrote: >>> On 05/25/2010 10:00 AM, Avi Kivity wrote: >>>> The latter. Why is it less important? If you don't inherit the >>>> memory, you can't access it. >>>> >>>>> You can also pass /dev/shm fd's via SCM_RIGHTs to establish shared >>>>> memory segments dynamically. >>>> >>>> Doesn't work for anonymous memory. >>> >>> What's wrong with /dev/shm memory? >> >> The kernel treats anonymous and nonymous memory differently for >> swapping (see /proc/sys/vm/swappiness); transparent hugepages won't >> work for /dev/shm (though it may be argued that that's a problem with >> thp); setup (/dev/shm defaults to half memory IIRC, we want >> mem+swap); different cgroup handling; somewhat clunky (a minor >> concern to be sure). > > Surely, with mmu notifiers, it wouldn't be that hard to share > anonymous memory via an fd though, no? That's what I suggested with processfd(). I wouldn't call it easy but it's likely doable. Whether it's mergable is a different issue. -- error compiling committee.c: too many arguments to function