Measure pipeline I/O latency

[Arun Raghavan]

On Wed, 21 Dec 2016, at 12:24 PM, Lijia (George Lee, Euler) wrote:
> I am working on ultra-low latency pipeline design for GStreamer 1.10.x,
> with that goal the primary step should measure the total real processing
> latency across each element which the overall pipeline makes up of, i.e.
> pipeline I/O latency. Even though there is latency compensation mechanism
> from source to sink in the pipeline, but it is still not what I am
> looking for.
> 
> On the other hand I am not sure whether existing GStreamer release has
> built-in latency metrics mechanism for respective each element or overall
> pipeline? Maybe we need re-invent such kind of this metrics for
> GStreamer.

We do have the GstTracer framework which might let you break things down
to at least how much time a buffer spends within each element, but if
you're looking for sources of I/O latency, you might find something like
latencytop or ftrace more helpful (since they are able to perform more
system-wide profiling which might be relevant in the case of I/O).

-- Arun