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Performance decrease with PGI 12.1
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xlapillonne



Joined: 16 Feb 2011
Posts: 69

PostPosted: Thu May 10, 2012 12:04 am    Post subject: Reply with quote

Hi Mat,

Thanks for the reply. I however tried on our latest install:
pgi 12.4 + cuda 4.2 and I got:
_977 : 28962 us (measured with nvidia profiler)

Which is better, but still much slower than what I used to get with 3.2. Wihch version of the PGI compiler did you use to get this 23011 us ?

Concerning your second remark I am not so sure that one is willing to put the vector on the inner loop as it is not the stride one index (for kernel l_911).
For other codes with similar loop structure, it was so far always faster to have the gang and vector on the outer loop (using the parallel construct with a cray compiler), the outer loop corresponding here to the stride-1 index. Unfortunately I haven't got yet an OpenAcc version of this code.

Best regards,

Xavier
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mkcolg



Joined: 30 Jun 2004
Posts: 6213
Location: The Portland Group Inc.

PostPosted: Thu May 10, 2012 10:02 am    Post subject: Reply with quote

Hi Xavier,
Quote:

Wihch version of the PGI compiler did you use to get this 23011 us ?
12.4 but the difference is that I used CUDA 4.1. With CUDA 4.2, I also see the 29000.

Quote:
Concerning your second remark I am not so sure that one is willing to put the vector on the inner loop as it is not the stride one index (for kernel l_911).
I understand, but this is solvable.

- Mat
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