Kernel Profiling!

[somu_peri]

Can vtune be used to find out performance analysis of the linux kernel (2.4.xx) ?
More specifically, give a split of time spend in each of the kernel functions ( whether the kernel had to context switch processes) etc?
S

[jeffrey-gallagher]

You can run a sampling experiment on the kernel; but you can't run a callgraph experiement on the kernel.

cheers,

jdg

[ewe]

I've tried various different things, but so far I can't get any sampling data from my kernel. When the remote monitor (Windows) contacts the Linux machine, I see this from vtserver:

001 12/01/06 12:13:00 received request from ewe@
001 12/01/06 12:13:00
001 12/01/06 12:13:00 sampling run started ...

-------------------------------------------------------------------------

**! LIBVSAMP Error:( 306 ) Module query failed.

-------------------------------------------------------------------------

I try using "rmmod_vtune" followed by "insmod-vtune" as suggested in the help. Several times. My vtune devices seem to present in /dev after the module loads.

I am not launching any remote application (I figured I didn't need to since I am trying to sample the kernel). Is there a specific way to setup vtune in order to sample the kernel? Should I list any modules of interest, or launch some kind of dummy application?

Thanks...

[aokunev]

Hi

It seems something wrong with vtune sampling driver configuration. It has been compiled without module enumeration support. Can you please submit this issue to Premier? Please attach the ountpu and logs of /opt/intel/vtune/bin/vtqfagent run.

As a workaround you may try to boot your system with any Linux kernel from the list of supported OSes, like Red Hat 4 or Novell SuSE 10. Is it possible?

regards, Andrei

[ewe]

Argh... I am losing my system today, so I have to suspend work on my profiling for now.

If and when I can work on this again, I would like to try and clarify what you are asking:

- I compiled the vtune driver myself (the kernel module). It appeared to build fine with no problems. Are you saying that I may have misconfigured it, or the kernel, and not included support for module enumeration? Because this is entirely possible! If there is a way to configure this option, could you tell me what it is? I read the build-driver script and Makefile but didn't see anything like this.

- The libvsamp.so library was pre-compiled. It looks like this is where the error is coming from (although I suppose it may be coming from the kernel module via the library; sorry, I don't know a lot about the driver and library work right now). You're not saying there is a problem with this library, right?

My system is using RHEL4, 2.6.9-42 kernel. Do you think this is causing the issue?

Finally, I could not find any of the log files you mentioned...

Thanks
Ed

[aokunev]

Hi Ed

I've got some more clarifications from developers:
Thiserror occurs when the sampling library, linuxsubs.so,is unable to perform kernel module enumeration.Under kernel 2.6, linuxsubs.so reads/proc/modulesto do this. Do you have SELinux enabled?

Do you use RedHat 4 update 4 distribution? Can you please let me know what is VTune
version you've tried? You may want to try 8.0.2 or wait several days for 8.0.3. Once you
installed them - please publish the output of vtqfagent run.

It would be great if you forward the issue to Premier.

Regards, Andrei