CUDA Event

CUDA Event
→ Stream 내부 명령에 흐름 중, 특정 지점에 표시를 남기는 것(일종의 표시 → marker)

• Creation and Destruction
  
  • cudaError_t cudaEventCreate (cudaEvent_t* event);
  • cudaError_t cudaEventDestory (cudaEvent_t event);
• Recording Events
  • cudaError_t cudaEventRecord (cudaEvent_t event, cudaStream_t stream = 0);
    • stream에 event 발생 위치를 표시함
    • stream에서 꺼내질 때 정보가 event에 기록됨
• Synchronization / Querying
  • cudaError_t cudaEventSynchronize (cudaEvent_t event);
    • 해당 event 발생까지 대기
  • cudaError_t cudaEventQuery (cudaEvent_t event);
    • 해당 event 발생 여부 확인
• Measure the elasped time
  • cudaError_t cudaEventElapsedTime (float* ms, cudaEvent_t start, cudaEvent_t stop);
    • start와 end 사이에 소요된 시간을 milliseconds 단위로 계산

[시간 측정 사용 예시]

//create two events
cudaEvent_t start, stop;
cudaEventCreate(&start);
cudaEventCreate(&stop);
 
cudaEventRecord(start); //record start event on the default stream
 
kernel <<< grid, block >>> (arguments); //execute kernel
 
cudaEventRecord(stop); //record stop event on the default stream
cudaEventSynchronize(stop); //wait until the stop event completes
 
//calculate the elapsed time between two events
float time;
cudaEventElapsedTime(&time, start, stop);
 
//clean up the two events
cudaEventDestroy(start);
cudaEventDestroy(stop);