PAPI error on AMD Opteron 6180 (romulus)

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PAPI error on AMD Opteron 6180 (romulus)

Postby fgsong » Mon Nov 07, 2011 4:22 pm

Hi,

I'm trying to measure a native event on an AMD multicore machine (our 48-core romulus). The event name is "CPU_TO_DRAM_REQUESTS_TO_TARGET_NODE:*". There is no error if I start less than 5 threads, but then PAPI_read() starts to report errors if I have more threads (e.g., 6, 12 threads).
And here is the error information: Error in PAPI_read: PAPI_ESBST. BTW, I'm using PAPI 4.2.0.

Do you know what would be the reasons for the error?

Thanks,
Fengguang
fgsong
 
Posts: 4
Joined: Mon Nov 07, 2011 4:08 pm

Re: PAPI error on AMD Opteron 6180 (romulus)

Postby vweaver1 » Wed Nov 09, 2011 11:50 am

fgsong wrote:Hi,

I'm trying to measure a native event on an AMD multicore machine (our 48-core romulus). The event name is "CPU_TO_DRAM_REQUESTS_TO_TARGET_NODE:*". There is no error if I start less than 5 threads, but then PAPI_read() starts to report errors if I have more threads (e.g., 6, 12 threads).
And here is the error information: Error in PAPI_read: PAPI_ESBST. BTW, I'm using PAPI 4.2.0.

Do you know what would be the reasons for the error?



This is strange. It's possible that that's a northbridge event; in that case it can only be used by one thread per core. I would think you'd be able to work on more than 5 threads though, I think you'd get at least 8. Are you pinning the threads to a CPU?
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Re: PAPI error on AMD Opteron 6180 (romulus)

Postby fgsong » Wed Nov 09, 2011 12:37 pm

Yes, I tried to pin 6 threads to 6 numa nodes, but there is still the same error. 5 threads are OK.

Thanks,
Fengguang
fgsong
 
Posts: 4
Joined: Mon Nov 07, 2011 4:08 pm

Re: PAPI error on AMD Opteron 6180 (romulus)

Postby fgsong » Wed Nov 09, 2011 12:49 pm

My mask was not correct.
OK, now I find that I could run 8 threads if they are bound to 8 numa nodes (or 8 memory controllers).
The error happens if there are more than 8 threads.

Thanks,
Fengguang
fgsong
 
Posts: 4
Joined: Mon Nov 07, 2011 4:08 pm

Re: PAPI error on AMD Opteron 6180 (romulus)

Postby fgsong » Tue Nov 22, 2011 11:03 am

Does it mean it is not supporting one thread per core?

Thanks,
Fengguang
fgsong
 
Posts: 4
Joined: Mon Nov 07, 2011 4:08 pm


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