Advanced_GPU_talk

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Synchronisation • Device-wide sync: cudaDeviceSynchronize() • CPU will block until everything finishes • Synchronising a specific stream: cudaStreamSynhronize(stream) • CPU blocks until everything in the given stream finishes • Events • Insert Events into streams, synchronise or time with them • cudaEventRecord(event,stream) • cudaEventSynchronize(event) - for the CPU • cudaStreamWaitEvent(stream,event) - for a stream • cudaEventQuery(event) • cudaStreamAddCallback(stream, callback, u_data, flags)
Synchronisation CPU <strong>GPU</strong> stream 1 stream 2 stream 3 launch(s3) launch(s1) eventRecord(e1,s1) eventSynchronize(e1) streamWait(s1) Kernel 1 Kernel 0 launch(s2) launch(s3) eventRec(e2,s3) sW4E(s1,e2) launch(s1) Kernel 2 Kernel 3 do_something_on _CPU() Kernel 4
Page 1 and 2: Advanced GPU programming techniques
Page 3 and 4: “Usual way” cudaMemcpy(…) ker
Page 5 and 6: Why streams? • Concurrent CUDA op
Page 7 and 8: So what is a stream? • A sequence
Page 9 and 10: Default (NULL) stream • This is t
Page 11: Overlap Example cudaStream_t stream
Page 15 and 16: Priority streams • cudaStreamCrea
Page 17 and 18: Multi-GPU • You can control multi
Page 19 and 20: CUDA 6.0 • Unified Memory • Poi
Page 21 and 22: Tip #2 - multi GPU • Always try a
Page 23: Thank you! istvan.reguly@oerc.ox.ac

Advanced_GPU_talk

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