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

[Matthew Tippett <tippettm@gmail.com>]

The benchmark used was the sqlite subtest in the phoronix test suite.

My awareness and involvement is beyond "reading a magazine article", I 
can elaborate if needed, but I don't believe it is necessary.

Process for reproduction, assuming Karmic,

	# apt-get install phoronix-test-suite

         $ phoronix-test-suite benchmark sqlite

Answer the questions (test-names, etc, etc), it will download sqlite, 
build it and execute the test.  By default the test runs three timesand 
averages the results.  The results experienced should be similar to the 
values identified at

http://www.phoronix.com/scan.php?page=article&item=linux_2631_kvm&num=3

Which is approximately 12 minutes for the native, and about 60 seconds 
for the guest.

Given that the performance under the guest is expected to be around 60 
seconds, I would suggest confirming performance there first.

Regards,

Matthew

-------- Original Message  --------
Subject: Re: sync guest calls made async on host - SQLite performance
From: Dustin Kirkland <dustin.kirkland@gmail.com>
To: Matthew Tippett <tippettm@gmail.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>, Avi Kivity 
<avi@redhat.com>, RW <kvm@tauceti.net>, kvm@vger.kernel.org
Date: 10/07/2009 02:59 PM

> 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