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From: Avi Kivity <avi@redhat.com>
To: Kurt Yoder <ktykvm@yoderhome.com>
Cc: kvm@vger.kernel.org
Subject: Re: IO on guest is 20 times slower than host
Date: Wed, 25 Mar 2009 18:54:58 +0200	[thread overview]
Message-ID: <49CA61E2.3050400@redhat.com> (raw)
In-Reply-To: <A4758D2B-87DC-419A-86AD-7666A39E7961@yoderhome.com>

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


  reply	other threads:[~2009-03-25 16:55 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-03-25 15:23 IO on guest is 20 times slower than host Kurt Yoder
2009-03-25 16:13 ` Avi Kivity
2009-03-25 16:28   ` Kurt Yoder
2009-03-25 16:35     ` Avi Kivity
2009-03-25 16:51       ` Kurt Yoder
2009-03-25 16:54         ` Avi Kivity [this message]
2009-03-25 17:11           ` Kurt Yoder
2009-03-25 17:55             ` Avi Kivity
2009-03-25 18:51               ` Kurt Yoder
2009-03-26 10:16                 ` Avi Kivity
2009-03-27 13:53                   ` Kurt Yoder
2009-03-27 14:03                     ` Kurt Yoder
2009-03-27 14:10                       ` Kurt Yoder
2009-03-29 14:29                         ` Avi Kivity
2009-03-29 19:10                           ` Avi Kivity
2009-03-31  9:59                             ` Joerg Roedel
2009-03-31 10:02                               ` Avi Kivity
2009-04-04 11:47                               ` Avi Kivity
2009-03-30 19:39                           ` Kurt Yoder
2009-03-31 15:15                             ` Kurt Yoder

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