Re: /proc/lock_stat "stuck"

From: Alan D. Brunelle
Date: Wed May 21 2008 - 07:09:35 EST

Peter Zijlstra wrote:
> On Tue, 2008-05-20 at 14:09 -0400, Alan D. Brunelle wrote:
>> I'm attempting to use /proc/lock_stat to gather some information during
>> some benchmarking runs, but what I find happens is as follows:
>> 1. I boot the system - 2.6.26-rc3 kernel + CONFIG_LOCK_STAT=y
>> 2. I can then look at /proc/lock_stat, and it has valid-looking values
>> 3. I wait a while, do some stuff, but when I look at /proc/lock_stat
>> again the values have not changed.
>> 4. If I clear the counters - echo 0 > /proc/lock_stat - the counters
>> never increase, and no information besides the headers are output when I
>> cat /proc/lock_stat.
>> Is there something that one needs to do to get counter updates?
> Did you get lockdep warnings? Those disable all lock debugging,
> including lockstat.

Hi Peter -

Yesterday, during boots I /was/ getting a problem with NVIDIA ck804xrom
registration problems - "Unable to register resource" - it did produce
a stack trace w/ lock calls in the stack. Since then I've cut /way/ back
on my .config, and I don't see that problem anymore, and the lock stats
seem to be updating correctly with this new .config. [If I have time
later today, I'll go back to the old .config and try to track down the
ck804xrom issue.]

Thanks for the hint about watching for lockdep issues,
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