LOCK_PROFILING

John Baldwin jhb at freebsd.org
Wed Aug 19 12:42:45 UTC 2009


On Wednesday 19 August 2009 2:30:25 am Pramod Srinivasan wrote:
> Hi Folks,
> 
> I have a difficult problem I am stuck with,  we had ported LOCK_PROFILING to
> FreeBSD 6.1 and is working fine on mips, but fails miserably on i386.
> 
> Just enabling lock profiling by the sysctl causes the cpu to reset.
> 
> root at bcdcpu3% sysctl debug.lock.prof.enable=1
> debug.lock.pr?  << cpu resets here
> 
> Has any one seen similar issues? Any pointers on where to start debugging
> this issue?
> 
> The suspicion is that the spin-lock is perhaps contributing to the problem,
> but have not been able to get to the bottom.

It sounds like a tripe fault.  I suspect you are recursing on your stack 
somehow leading to a double fault that faults again trying to get a lock to 
output to the console perhaps (that would explain the lack of double fault 
messages if that were the case).  Perhaps a lock used in the profiling is 
incorrectly being profiled?

-- 
John Baldwin


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