From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: IO on guest is 20 times slower than host Date: Wed, 25 Mar 2009 18:54:58 +0200 Message-ID: <49CA61E2.3050400@redhat.com> References: <49CA5825.7030201@redhat.com> <4AC00930-1EBB-4704-94CF-29478D07F03A@yoderhome.com> <49CA5D53.1080401@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Kurt Yoder Return-path: Received: from mx2.redhat.com ([66.187.237.31]:50369 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756106AbZCYQzG (ORCPT ); Wed, 25 Mar 2009 12:55:06 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: Kurt Yoder wrote: > > I upped the memory on the VM to 1 GB and ran the same test. It > actually got *slower*: > > me@guest:~$ free > total used free shared buffers cached > Mem: 1024224 131324 892900 0 1816 18328 > -/+ buffers/cache: 111180 913044 > Swap: 488248 0 488248 > me@guest:~$ sudo -s > me@guest:~# dd if=/dev/zero of=/bigfile count=100000 > 100000+0 records in > 100000+0 records out > 51200000 bytes (51 MB) copied, 22.2141 s, 2.3 MB/s > Wierd. Can you change the disk interface to ide to rule out virtio issues? (though dd should be running entirely in cache) Is your disk a raw volume or qcow file? -- error compiling committee.c: too many arguments to function