David,
Thanks for the additional information. I will try your test case on my
machine when I get a chance.
On Tue, Nov 10, 2009 at 4:45 PM, David Nellans <dnell...@cs.utah.edu> wrote:
> Hey Stephane,
>
> Sorry for not following up on this sooner - here is a bit more info on my
> own debugging process
>
> The dmesg dump was when using the "low latency desktop" option for preempt
> but with preemptable RCU turned off. By moving to "server"( no preempt)
> I am still able to lock up the machine occasionally - though it happens far
> less frequently. When it does happen there appears to be no dmesg output
> (or things are locking differently that oopses to a state
> where i can't dmesg)
>
> Moving to system-wide profiling instead of thread level appears to make the
> lockups disappear completely both with preempt on and off. I hammered the
> machine over the weekend and not a single lockup
> when using system-wide profiling vs every 6-10 runs when using preemption
> and every 10-20 maybe when preempt is off.
>
> Sorry this is so anecdotal - let me know if there is something I can do to
> provide more systematic testing for you.
>
> cheers
> -dave
>
>
>
> On Tue, 2009-11-10 at 16:32 +0100, stephane eranian wrote:
>
> David,
>
>
>
> Could you try recompiling your kernel without preemption turned on?
>
>
>
> On Sun, Nov 8, 2009 at 12:09 AM, David Nellans <dnell...@cs.utah.edu>
> wrote:
>
> I've been able to replicate what seems to be a race condition based bug.
> I can run many traces without a crash, and sometimes it will crash on the
> first attempt.
>
> I've attached a log of the dmesg output of what is happening. Please let
> me know if there is anything else I can provide that might help diagnose.
>
> ----------------------------------------
> From: *Manu Awasthi* <manu.awas...@gmail.com>
> Date: Tue, Nov 3, 2009 at 10:31 AM
> Subject: kernel panic with monitoring DRAM events
> To: perfmon2-devel@lists.sourceforge.net
>
>
> Hi all,
> I have been measuring memory events for the parsec benchmark suite on a
> dual socket, quad-core opteron machine with pfmlib version 3.9, kernel pfmon
> version 2.82 and kernel version 2.6.29.6 . This is what I use as my
> commandline option:
>
> >> pfmon --with-header --outfile=test1 --verbose -u --switch-timeout=100
> -eDRAM_ACCESSES_PAGE:HIT,DRAM_ACCESSES_PAGE:MISS,DRAM_ACCESSES_PAGE:CONFLICT,DRAM_ACCESSES_PAGE:ALL
> -eDRAM_ACCESSES_PAGE:DCT1_PAGE_HIT,DRAM_ACCESSES_PAGE:DCT1_PAGE_MISS,DRAM_ACCESSES_PAGE:DCT1_PAGE_CONFLICT,DRAM_ACCESSES_PAGE:ALL
> $PASEC_COMMAND
>
> The problem is, sometimes, over different runs of the same (multi-threaded)
> benchmark, the kernel panics and the machine freezes up. has anybody ever
> experienced something of this sort before? Or is there something that I am
> doing wrong? Is there a better way to measure these stats (system-wide
> monitoring?)?
>
> Any help is appreciated.
>
> Thanks,
> Manu
>
>
> -----------------------------
> David W Nellans
> dnell...@cs.utah.edu
>
>
>
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>
>
>
> -----------------------------
> David W Nellans
> dnell...@cs.utah.edu
>
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