From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54426) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VsohH-0007mV-Rf for qemu-devel@nongnu.org; Tue, 17 Dec 2013 02:04:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VsohD-0006ey-O6 for qemu-devel@nongnu.org; Tue, 17 Dec 2013 02:04:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38233) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VsohD-0006eu-GV for qemu-devel@nongnu.org; Tue, 17 Dec 2013 02:03:59 -0500 Date: Tue, 17 Dec 2013 15:03:50 +0800 From: Amos Kong Message-ID: <20131217070350.GA4270@amosk.info> References: <1386598213-8156-1-git-send-email-akong@redhat.com> <1386598213-8156-2-git-send-email-akong@redhat.com> <20131216123540.GB6582@grmbl.mre> <20131217055214.GF6582@grmbl.mre> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131217055214.GF6582@grmbl.mre> Subject: Re: [Qemu-devel] [PATCH RFC 1/2] rng-egd: improve egd backend performance List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Amit Shah Cc: varadgautam@gmail.com, qemu-devel , Anthony Liguori On Tue, Dec 17, 2013 at 11:22:14AM +0530, Amit Shah wrote: > On (Mon) 16 Dec 2013 [15:19:31], Anthony Liguori wrote: > > On Mon, Dec 16, 2013 at 8:36 AM, Amit Shah wrote: > > > On (Mon) 09 Dec 2013 [22:10:12], Amos Kong wrote: > > >> Bugzilla: https://bugs.launchpad.net/qemu/+bug/1253563 > > >> > > >> We have a requests queue to cache the random data, but the second > > >> will come in when the first request is returned, so we always > > >> only have one items in the queue. It effects the performance. > > >> > > >> This patch changes the IOthread to fill a fixed buffer with > > >> random data from egd socket, request_entropy() will return > > >> data to virtio queue if buffer has available data. > > >> > > >> (test with a fast source, disguised egd socket) > > >> # cat /dev/urandom | nc -l localhost 8003 > > >> # qemu .. -chardev socket,host=localhost,port=8003,id=chr0 \ > > >> -object rng-egd,chardev=chr0,id=rng0,buf_size=1024 \ > > >> -device virtio-rng-pci,rng=rng0 > > > We have a wiki about about configing egd. http://fedoraproject.org/wiki/QA:Testcase_Virtualization_VirtioRNG > > > First thing I can think of is the egd protocol has a length field in > > > the header, and if that isn't properly filled, the results are bound > > > to be erratic. The header setup in rng-egd.c is correct, we can check the debug output of egd.pl > > The test is bogus. > > > > egd is a protocol. You can't just pipe /dev/urandom into it. In my test host, When I use the egd-socket, it is very slow. So I use a quick souce /dev/urandom, we ignore the egd protocol here, it might be wrong. > Can you suggest a way to test this the right way? It seems we should still use egd.pl to setup a daemon socket. But how to make it very quick? We can't verify the performance improvement if the source is too slow. Can we use "--bottomless" option for egd.pl? it will not decrement entropy count. When I use this option, the speed (without my patches) is about 13 kB/s. > Amit -- Amos.