Doca Dma task latency

I use Nvidia- Bluefueld-2.
I read the host’s data from DPU and measured the execution time for doca dma.
Doca version is 2.5.0107
I used the provided doca sample (eg.dma_copy_dpu).


/* Submit DMA task */
result = doca_task_submit(task);
if (result != DOCA_SUCCESS) {
	DOCA_LOG_ERR("Failed to submit DMA task: %s", doca_error_get_descr(result));
	doca_task_free(task);
	goto destroy_dst_buf;
}

resources.run_main_loop = true;

/* Wait for all tasks to be completed and context stopped */
clock_gettime(CLOCK_MONOTONIC, &start);
while (resources.run_main_loop) {
	if (doca_pe_progress(state->pe) == 0)
		continue;

}
clock_gettime(CLOCK_MONOTONIC, &end);

I measured the time for the task as above.
The result is shown below.


[07:47:17:915830][3127561][DOCA][INF][dma_copy_dpu_main.c:63][main] Starting the sample
[07:47:17:973569][3127561][DOCA][INF][dma_common.c:314][dma_state_changed_callback] DMA context is running
[07:47:17:975177][3127561][DOCA][INF][dma_common.c:245][dma_memcpy_completed_callback] DMA task was completed successfully
[07:47:17:991954][3127561][DOCA][INF][dma_common.c:303][dma_state_changed_callback] DMA context has been stopped
[07:47:17:991989][3127561][DOCA][INF][dma_copy_dpu_sample.c:310][dma_copy_dpu] Remote DMA copy was done Successfully
[07:47:17:992007][3127561][DOCA][INF][dma_copy_dpu_sample.c:312][dma_copy_dpu] Memory content: This is a sample piece of text
[07:47:17:992027][3127561][DOCA][INF][dma_copy_dpu_sample.c:313][dma_copy_dpu] DMA Copy Latency: 16815498.00 nanoseconds
[07:47:17:992059][3127561][DOCA][INF][dma_copy_dpu_sample.c:314][dma_copy_dpu] DMA Copy Latency: 16.82 milliseconds
[07:47:17:992080][3127561][DOCA][INF][dma_copy_dpu_sample.c:321][dma_copy_dpu] Host sample can be closed, DMA copy ended
[07:47:17:993201][3127561][DOCA][INF][dma_copy_dpu_main.c:99][main] Sample finished successfully


As you can see, it came out to 16.82 ms.
Why?
Did I identify the wrong part performing the DMA operation?
In doca 1.x, latency was measured in us units.

Please provide a solution.

Hi,

Thanks for your question.
The performance may be affected by multiple factors, and to understand that more information about the setup will be required.
In such cases, in order to perform a deeper investigation we would ask you to open a support case in Nvidia portal, or just send an email with all the details to enterprisesupport@nvidia.com, and this case will be handled according to the support entitlement.

Best Regards,
Anatoly