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OpenACC on K20 - max data chunk size

 
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leonip



Joined: 21 Mar 2014
Posts: 5

PostPosted: Sun Mar 23, 2014 7:22 am    Post subject: OpenACC on K20 - max data chunk size Reply with quote

I'm a graduating student involved in a performance analysis of a scientific application that I'm porting to OpenACC (I'm using PGI 14.1).

In some tests, I noticed that (thanks to NVPP) maximum chunk size of data transferred to device is 16 MB.

Is this an arch-dependent value? The device is a Kepler20s

Thanks in advance.

Paolo L.
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cparrott



Joined: 02 May 2011
Posts: 146

PostPosted: Mon Mar 24, 2014 2:11 pm    Post subject: Reply with quote

Paolo,

The chunk size can be adjusted via an environment variable: PGI_ACC_BUFFERSIZE.

For example, if you wish to use a 32 MB buffer size, you could do the following in bash:

export PGI_ACC_BUFFERSIZE=32M

Hope this helps.

Best regards,

+chris
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leonip



Joined: 21 Mar 2014
Posts: 5

PostPosted: Mon Mar 24, 2014 5:58 pm    Post subject: Reply with quote

Thank you Chris, this is exactly what I need.

Have a nice day.

Paolo
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