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RE: [Xen-devel] Re: XENOPROF Problem
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Acive domain profiling has not been well tested with
pvops kernel.
Dulloor who ported xenoprof parches to the pvops kernel
said in a previous post that he would look into that but not sure if he
did.
For now your alternatives are:
- Use passive domain prifiling
instead
- Use 2.6.18-xen with Xen 4.0 or latest unstable
which are known to work with active domain profiling
Renato
Hi Ahmad,
I'm certainly not a Xenoprof expert, but I've
learned a bit about it by trial and error, with help from the xen-devel list.
I've taken the liberty of Cc:ing xen-devel so that others more knowledgeable
than me can help you. I haven't tried passive domains yet, and I'll say up
front that I don't know why Xenoprof isn't working for you with passive
domains.
On 02/11/10 13:37, Ahmad Hassan wrote:
Hi Andrew, I need help in using xenoprof. I
installed the xenoprof on Dom0 and DomU as follows:
That looks right to me. You
also need Xenoprof support in your dom0 kernel. If you're using one of the
kernels from the Xen source tree and you can `modprobe oprofile` successfully,
you should be ok.
I am interested in measuring profiling overhead in
XEN. So which kind of event should I capture.
You want
to measure the overhead of the profiler itself? I guess you get that "for
free" -- time spent in oprofile kernel code should show up in opreport in
dom0, I think.
Which performance counter you use depends on what you're
trying to measure. If you just want to find out where CPU time is spent,
CPU_CLK_UNHALTED should do that for you. That's what I've been doing.
Is it possible to capture all the
events?
You can specify multiple events, though I
haven't tried it. The opreport web page talks about output for multiple events
here:
http://oprofile.sourceforge.net/doc/opreport.html#opreport-comparison
I'd
guess you'd just specify --event multiple times when you
--start-daemon.
I followed the following passive profiling
approach but I did not get any data.
Dom0:
opcontrol --reset Dom1: opcontrol --reset Dom0: opcontrol
--start-daemon --event=
CPU_IO_REQUESTS_TO_MEMORY_IO:1000000
--xen=/boot/xen-syms-3.4.1 --vmlinux=/boot/vmlinux
--passive-domains=1 --passive-images=/boot/vmlinux At the above
command, I get the warning as : /dev/oprofile/passive-domains Permission
Denied but daemon starts eventually
This is a
silly question, but you are running this as root, correct? If you are running
as root and getting this error, I think something is wrong either in Xen or
your dom0 kernel. `xm dmesg` may have error messages that give clues -- check
it before and after starting the daemon.
Dom0: opcontrol --start AFTER 30 MINUTE Dom0:
opcontrol –stop Dom0: opcontrol --dump Dom0: opcontrol
–shutdown But when I try to "opreport -l" ti says that: "opreport
error: No sample file found: try running opcontrol --dump or specfiy a
session containing sample file" Can you please help me in
that? Thanks. Best Regards, Hassan http://cern.ch/ahmadh/portfolioErasmus
Student The University of Reading, UK Aristotle University of
Thessaloniki, Greece The University Of Carlos III, Madrid
Spain
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