Joel,
Thanks for helping me with my problem.
Good point about the disk activity. I had a problem with disk activity earlier,
which I determined to be caused by a hald process polling for the CD drive. Once
I killed it (no disk activity afterwards), performance in hdparm increased
dramatically (from 300MB/s to 1200MB/s). However, the standard performance that
I normally get should be 4000MB/s. Also, CPU benchmarks are still ~100x slower.
I''m currently testing dom0 performance only without any domUs running.
Of course, when the transient performance issue happens in the dom0, it also
happens in the domUs (which was how we discovered the problem in the first
place). We''ve narrowed it down to something in the dom0 Xen install.
Dan
> CC: xen-users@lists.xensource.com
> From: xen@joelrichard.com
> To: danz@umich.edu
> Subject: Re: [Xen-users] Transient xen performance issue
> Date: Wed, 11 Mar 2009 08:46:39 -0400
>
> Dan,
>
> You didn''t mention disk activity or whether the CPUs are waiting
on
> anything. I have noticed (at least in my limited experience) that when
> a DomU is using a lot of disk, the Dom0 will show that the CPU (using
> plain old "top") is spending a significant amount of time waiting
for
> the I/O.
>
> Here''s my top header. Note that this machine is mostly idle. :)
>
> top - 15:41:57 up 5:59, 2 users, load average: 0.00, 0.00, 0.00
> Tasks: 98 total, 1 running, 97 sleeping, 0 stopped, 0 zombie
> Cpu(s): 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.2%wa, 0.0%hi,
> 0.0%si, 0.0%st
>
> But if you have a lot in "wa" (I/O wait) that could be the source
of
> some trouble.
>
> In other words, if the server is not doing what you want it to be
> doing, you need to figure out what it IS doing. :)
>
> --Joel
>
>
> On Mar 9, 2009, at 10:49 PM, Dan Zhang wrote:
>
> > I''m installing Xen with the OpenSUSE 10.2 distro and the
> > bigsmp-2.6.18.8-0.13.i586 kernel. However, I occasionally get insane
> > amounts of slowdown (almost 100x) in dom0. On bootup, performance is
> > normal. After an undeterministic period of time, I get this crazy
> > amount of slowdown. I''m not sure why this is the case and I
have
> > spent a long time trying to figure it out. There are no background
> > processes running and nothing CPU intensive shows up on top or ps aux.
> >
> > One point of interest is that when I run ''lsmod'',
the modules
> > ide_core and ide_disk are missing. I tried installing them but it
> > seems that they aren''t necessary. Since performance is fine
on
> > startup, I''m not sure if this is a problem.
> >
> > I''m installing and compiling Xen 3.3.0 from scratch by using
"make
> > world", etc.
> >
> > Does anyone have any ideas or suggestions?
> >
> > Thanks!
> >
> > Dan
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@lists.xensource.com
> > http://lists.xensource.com/xen-users
>
>
>
> Joel Richard
> The Richard Group
> joel@richard-group.com
> 703-584-5802
>
>
>
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