RE: PATCH Multithreaded core dump support for the 2.5.14 (and 15) kernel.

From: Gross, Mark (mark.gross@intel.com)
Date: Tue May 14 2002 - 11:38:28 EST


See attached unit test code. its not very pretty...

These are NOT exhaustive tests, yet they are a reasonable attempt at unit
testing / exercising the feature to check for stability issues. My stress
test was to induce core dumps in these test programs while running the IBM
chat room benchmark. The XMM.c program was written by Rao Bharata as part
of the 2.4.17 tcore testing. I don't remember who wrote test.c, but ptest.c
is my fault.

I know that the i386 elf core file note sections only contain the class of
register data that's restored by __switch_to. So I suppose a kernel thread,
like the migration_thread, or ksoftirq "could" dump core and GDB could do a
bt on such a dump. However; these note sections only contain any data that
can be accessed from a non-privileged processor modes and your mileage will
vary.

--mgross

> -----Original Message-----
> From: Erich Focht [mailto:efocht@ess.nec.de]
> Sent: Tuesday, May 14, 2002 8:36 AM
> To: mark.gross@intel.com
> Cc: Linus Torvalds; linux-kernel@vger.kernel.org; Vamsi Krishna S .
> Subject: Re: PATCH Multithreaded core dump support for the 2.5.14 (and
> 15) kernel.
>
>
> Hi Mark!
>
> Thanks for sending the new patch, I'd be interested in the
> testprograms :-)
>
> BTW: any idea what happens when a thread which is suspended
> happens to be in
> kernel mode? Guess this could be possible with 2.5.X... Does
> gdb handle that?
>
> Regards,
> Erich
>
> On Monday 13 May 2002 21:17, you wrote:
> > The following patch for 2.5.14 kernel, applies cleanly to the 2.5.15
> > kernel.
> >
> > This work has been tested on the 2.5.14 kernel using a few pthread
> > applications to dump core, from SIGQUIT and SIGSEV. This
> unit test has been
> > done on both 2 and 4 way systems. Further, some stress
> testing has been
> > done where, the core files have been created while the
> system is under
> > schedule stress from the chat room benchmark running while
> creating the
> > core files. This implementation seems to be quit stable
> under a busy
> > scheduler, YMMV. These test programs are available uppon request ;)
>
>
>





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