Any issues with fork/exec should be orthogonal to the
"sampling stopped" issue within any single thread or process.

My point about SIGIO is that there's a robust idiom for
handling this stuff without having to go to queued events.


Philip Mucci wrote:
> Rob,
> 
> These issues are all solved in the latest copy of PAPI by using a RT 
> signal. If you have a test case on any platform where this isn't true, 
> please send it along. Marks note only reflects changes made in the PAPI 
> library, not any code that cray has, nor the Perfmon2 code.
> 
> However, I can assure you that the issues here are related to PAPI's 
> inability to properly handle a running context across fork/exec.
> 
> Phil
> 
> 
> On Apr 18, 2008, at 5:09 PM, Rob Fowler wrote:
> 
>> Typically, two SIGIOs are delivered:  one occurs with the
>> first event; all visible events are handled with SIGIO blocked; when
>> the handler returns, a second SIGIO is delivered to indicate the
>> occurrence of the 2nd through Nth events.  Since all of the events
>> may have already been handled before the 2nd SIGIO is delivered, the
>> signal handler also needs to be able to deal with the "no events
>> pending" case.
>> An aside:
>>
>> Mark K sent a note to me that
>> said "On CNL 2.1 and perfmon 2.3, I was able to complete 1-hour runs
>> with multiple threads, at 2,000 interrupts/second, 10,000/second and
>> even 100,000/second without dropping interrupts."
>>
>> It would begood if Cray pushed their fixes back to the world.

-- 
Robert J. Fowler
Chief Domain Scientist, HPC
Renaissance Computing Institute
The University of North Carolina at Chapel Hill
100 Europa Dr, Suite 540
Chapel Hill, NC 27517
V: 919.445.9670
F: 919 445.9669
[EMAIL PROTECTED]

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