From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=44996 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OEpTw-0006OD-R7 for qemu-devel@nongnu.org; Wed, 19 May 2010 16:03:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OEpTu-0006nO-Qc for qemu-devel@nongnu.org; Wed, 19 May 2010 16:03:08 -0400 Received: from smtp2.goneo.de ([82.100.220.82]:38436) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OEpTu-0006n3-Li for qemu-devel@nongnu.org; Wed, 19 May 2010 16:03:06 -0400 Message-ID: <4BF443EA.3020405@polarzone.de> Date: Wed, 19 May 2010 22:02:50 +0200 From: Udo Lembke MIME-Version: 1.0 References: <0af691d779965663abdd7bc708c2ad7bce2f6da0.1273699506.git.mtosatti@redhat.com> <659C91C0-E58A-43F6-A262-A15613E84FD3@suse.de> <4BED70B3.50202@redhat.com> <679AB14D-A9CC-437E-932F-AC13CAC26BA5@suse.de> <4BED7220.9060203@siemens.com> <4BF3B5F9.6020901@polarzone.de> <4BF41025.9020107@redhat.com> In-Reply-To: <4BF41025.9020107@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH 10/12] kvm: enable smp > 1 List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org Avi Kivity schrieb: > On 05/19/2010 12:57 PM, Udo Lembke wrote: >> Jan Kiszka schrieb: >>> ... >>> --enable-io-thread? >>> >>> If you had it disabled, it would also answer my question if -smp works >>> without problems without that feature. >>> >>> Jan >>> >> Hi, >> i have a dumb question: what is the "--enable-io-thread"? Is this a >> kvm-switch? > > It's a ./configure switch for upstream qemu (don't use with qemu-kvm > yet). > >> My kvm 0.12.4 don't accept this switch. I'm know only "threads=n" as >> smp-parameter and "aio=threads" as drive-parameter. >> >> Because i look for a solution for a better io-performance of >> windows-guest with more than one cpu... > > Unrelated, what are your smp issues? > If i use one cpu i got a good io-performance: e.g. over 500MB/s at the profile "install" of the io-benchmark h2benchw.exe. ( aio=threads | SAS-Raid-0 | ftp://ftp.heise.de/pub/ct/ctsi/h2benchw.zip | hwbenchw.exe -p -w iotest 0) The same test but with two cpus gives results between 27 and 298 MB/s! Also in real life it's noticeable not only with an benchmark. I use a win-vm with two cpu for postscript-ripping and have a performance drop due to the bad io. Udo