Re: sync guest calls made async on host - SQLite performance

[Dustin Kirkland <dustin.kirkland@gmail.com>]

On Wed, Oct 7, 2009 at 11:53 AM, Matthew Tippett <tippettm@gmail.com> wrote:
> When you indicated that you had attempted to reproduce the problem, what
> mechanism did you use?  Was it Karmic + KVM as the host and Karmic as
> the guest?  What test did you use?


I ran the following in several places:
  a) on the system running on real hardware,
    time dd if=/dev/zero of=$HOME/foo bs=1M count=500
    524288000 bytes (524 MB) copied, 9.72614 s, 53.9 MB/s
  b) in an vm running on qemu-kvm-0.11 on Karmic
    time dd if=/dev/zero of=$HOME/foo bs=1M count=500 oflag=direct
    524288000 bytes (524 MB) copied, 31.6961 s, 16.5 MB/s
  c) in a vm running on kvm-84 on Jaunty
    time dd if=/dev/zero of=$HOME/foo bs=1M count=500 oflag=direct
    524288000 bytes (524 MB) copied, 22.2169 s, 23.6 MB/s

Looking at the time it takes to write a 500MB file to a real hard
disk, and then inside of the VM.  If I were to experience the problem
on Karmic, I would have seen this dd of a 500MB file take far, far
less time than it takes to write that file to disk on the real
hardware.  This was not the case in my testing.

> I will re-open the launchpad bug if you believe it makes sense to
> continue the discussions there.

Please re-open the bug if you can describe a real test case that you
used to demonstrate the problem.  Without being rude, it's hard for me
to work from a bug that says a magazine article says that there's a
bug in the Ubuntu distribution of qemu-kvm-0.11.

If you can provide clear steps that you have used to experience the
problem, then I will be able to take this issue seriously, reproduce
it myself, and develop a fix.

:-Dustin