Crash/trace when starting oprofile

Crash/trace when starting oprofile

[Pablo Llopis]

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Hello Xen developers,

I sent a similar message to xen-users about a week ago, did not obtain any
response and only now realized that I should have sent this here instead (
http://xenoprof.sourceforge.net/ says to write to this list). Apologies if
you see this message twice.

I am trying to run oprofile in my dom0, but get a crash (displayed as a call
 trace in dmesg) as soon as I run opcontrol --start.
I assume this is a Xen problem because the first line reads:

WARNING: at /build/buildd/linux-3.0.0/arch/x86/xen/enlighten.c:732
xen_apic_write+0x1a/0x20()

The corresponding full dmesg output is available at the following pastebin:
http://pastebin.com/mRuqkPSV
Note that the crash doesn't really crash Xen, it's just a call trace that
is output, everything but oprofile seems to be working.

My setup:
Xen version is 4.1.1, booting a x86_64 3.0.0-17 dom0 kernel. Oprofile is
version 0.9.6 and supports the --xen option. Those are the latest packages
available for ubuntu oneiric for both kernel and Xen. I chose to install
from ubuntu packages for convenience (not having to build Xen from scratch,
etc..)
CPU is an AMD Opteron Processor 6168.

How to reproduce:
Right before I run opcontrol --start, I do: opcontrol --setup
--vmlinux=/usr/lib/debug/boot/vmlinux-vmlinux-3.0.0-17-server
I tried with --no-vmlinux, same result. The trace appears when I run
opcontrol --start.

I also tried booting off the aforementioned kernel directly as well, with
no hypervisor involved at all, and did not get anycall traces or crashes
(obviously, since Xen is no longer involved, but I wanted to make sure
there isn't something else going on).

Googling didn't help much, I just found references to other pastebins with
similar traces, but could not find any post referencing those pastes.

I am not sure if this issue is known or has even been fixed in development
versions.
(I tried installing the development version from the master branch, but
couldn't get it to run since "make install" would not install user-level
executables; tried installing manually from tools/python but got lots of
errors I have not been able to solve -- but that is a separate issue).

I am not sure about what is going on and how to proceed. I would appreciate
any suggestions to solve this issue. I suspect this is a bug in Xen.

Thank you in advance,

Pablo

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Re: Crash/trace when starting oprofile

[Wei Liu]

On Wed, 2012-03-28 at 15:55 +0100, Pablo Llopis wrote:
> Hello Xen developers, 
> 
> 
> I sent a similar message to xen-users about a week ago, did not obtain
> any response and only now realized that I should have sent this here
> instead (http://xenoprof.sourceforge.net/ says to write to this list).
> Apologies if you see this message twice.
> 

There are some patches floating around on xen-devel:

http://marc.info/?l=xen-devel&m=132779518918042&w=2
http://marc.info/?l=xen-devel&m=132708552318073&w=2



Wei.

Crash/trace when starting oprofile

[Pablo Llopis]

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Thank you, I will try Michael's patches on a vanilla 3.0 or 3.2 kernel and
report back.
However, on first sight the patches enable profiling on unprivileged guests
(although the author calls it passive profiling, which as far as I know is
the opposite), and I am trying to do unprivileged dom0 profiling. Lets hope
this helps!

On Wed, Mar 28, 2012 at 5:43 PM, Wei Liu
<wei.liu2@citrix.com<javascript:_e({}, 'cvml',
'wei.liu2@citrix.com');>
> wrote:

> On Wed, 2012-03-28 at 15:55 +0100, Pablo Llopis wrote:
> > Hello Xen developers,
> >
> >
> > I sent a similar message to xen-users about a week ago, did not obtain
> > any response and only now realized that I should have sent this here
> > instead (http://xenoprof.sourceforge.net/ says to write to this list).
> > Apologies if you see this message twice.
> >
>
> There are some patches floating around on xen-devel:
>
> http://marc.info/?l=xen-devel&m=132779518918042&w=2
> http://marc.info/?l=xen-devel&m=132708552318073&w=2
>
>
>
> Wei.
>
>
>

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Re: Crash/trace when starting oprofile

[Pablo Llopis]

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I tried the patches on a vanilla 3.2.13 kernel (patches applied cleanly
\o/) with success!

In case this is helps anybody in the future, the issue here was that
ubuntu's 3.0.0.x kernels with xen-hypervisor 4.1.1 and oprofile 0.9.6 did
not work properly.
In addition to building a stock kernel, I had to build the hypervisor from
source in order to obtain the xen-syms image corresponding to hypervisor
version 4.1.1, the one you specify with --xen to oprofile. (I did this with
apt-get source in order to ensure that I was obtaining the same version).

Thank you for your help,

Pablo

On Wed, Mar 28, 2012 at 10:59 PM, Pablo Llopis <pllopis@arcos.inf.uc3m.es>wrote:

> Thank you, I will try Michael's patches on a vanilla 3.0 or 3.2 kernel and
> report back.
> However, on first sight the patches enable profiling on unprivileged
> guests (although the author calls it passive profiling, which as far as I
> know is the opposite), and I am trying to do unprivileged dom0 profiling.
> Lets hope this helps!
>
>
> On Wed, Mar 28, 2012 at 5:43 PM, Wei Liu <wei.liu2@citrix.com> wrote:
>
>> On Wed, 2012-03-28 at 15:55 +0100, Pablo Llopis wrote:
>> > Hello Xen developers,
>> >
>> >
>> > I sent a similar message to xen-users about a week ago, did not obtain
>> > any response and only now realized that I should have sent this here
>> > instead (http://xenoprof.sourceforge.net/ says to write to this list).
>> > Apologies if you see this message twice.
>> >
>>
>> There are some patches floating around on xen-devel:
>>
>> http://marc.info/?l=xen-devel&m=132779518918042&w=2
>> http://marc.info/?l=xen-devel&m=132708552318073&w=2
>>
>>
>>
>> Wei.
>>
>>
>>
>

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