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[erman_amd]

How to use the Stream Timeline in Visual Studio

A simple question.

I collect application trace and the stream timeline displayed information as below. (GPU Radeon HD 5870)

Data Transfer:

Name:12.0 KB READ_BUFFER

Device:Cypress

Command Type: CL_COMMAND_READ_BUFFER

Queued Time:2704.881 millisecond

Submit Time:2704.891 millisecond

Start Time:2705.210 millisecond

End Time: 2705.295 millisecond

Duration: 85.280 microseconds

clEnqueue API Name: clEnqueueReadBuffer

clEnqueue API Start Time: 2704.875 millisecond

clEnqueue API End Time: 2705.333 millisecond

clEnqueue API Duration: 458.259 microseconds

Transfer Rate: 137.415 MB/s

Transfer Size: 12.000 KB

Why the transfer rate only 137.415 MB/s? Any comment about this?

[himanshu_gautam]

ermen,

You should try to copy a larger chunk of data. Also do that multiple times and then calculate the Transfer rate.

There can be a lot of reasons for such transfer rate including GPU warm-up times, memory access pattern, and channel conflicts. You can refer to the GLobal Memory Bandwidth Sample to know how to get better memory transfer rates.