When the trace buffers are saved to disk?

When the trace buffers are saved to disk?

[Adel Belkhiri]

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Hi all,

Recently, while tracing applications from the apps and examples
directories, I became confused about when the trace buffer is written to
disk. Is the trace data saved only when rte_save_trace() is called, or does
it also automatically save when the buffer becomes full?

From my understanding, rte_save_trace() is invoked when the application
executes rte_eal_cleanup(). Does this mean the target application needs to
explicitly support tracing by calling rte_save_trace()—perhaps at regular
intervals—to dump the trace buffer to disk? Otherwise, will we only get a
fragment of the trace saved during rte_eal_cleanup() execution?

Thank you for clarifying this point.

Best,
Adel

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Re: When the trace buffers are saved to disk?

[Thomas Monjalon]

28/11/2024 20:17, Adel Belkhiri:
> Hi all,
> 
> Recently, while tracing applications from the apps and examples
> directories, I became confused about when the trace buffer is written to
> disk. Is the trace data saved only when rte_save_trace() is called, or does

It is rte_trace_save()

> it also automatically save when the buffer becomes full?

No, DPDK is not doing such thing without user agreement.

> From my understanding, rte_save_trace() is invoked when the application
> executes rte_eal_cleanup(). Does this mean the target application needs to
> explicitly support tracing by calling rte_save_trace()—perhaps at regular
> intervals—to dump the trace buffer to disk? Otherwise, will we only get a
> fragment of the trace saved during rte_eal_cleanup() execution?

Yes you get it right.

> Thank you for clarifying this point.

Thanks for asking.

If you think the doc below is not clear enough,
do not hesitate to submit a patch to make the doc better:

	https://doc.dpdk.org/guides/prog_guide/trace_lib.html