[LAD] DSP transients

[Will J Godfrey]

On Sun, 3 Sep 2017 10:59:53 -0400
Mark McCurry <mark.d.mccurry at gmail.com> wrote:

>On Sun, Sep 3, 2017 at 10:19 AM, Harry van Haaren <harryhaaren at gmail.com> wrote:
>> This won't tell you *where* in the code the issue is - but does give you a
>> reproducable test
>> case and some input on if DSP load is consistent. If you want to know
>> *where* in the code most of
>> the time is spent, then using linux perf tools or similar might be useful.
>
>If something more fine grained is desired I had some luck using valgrind to dump
>detailed statistics for every execution of the audio process() callback.
>Valgrind will tell you where the problem is as long as it's CPU bound and
>not memory/IO bound operations causing the issue.
>This was pretty helpful for smoothing out some of the overhead that
>ZynAddSubFX had
>in older versions.
>The writeup is somewhat rough, but my old notes for using valgrind to profile
>transient CPU load are stored at:
>http://log.fundamental-code.com/2013/09/07/profiling-realtime-code.html
>
>--Mark

Thanks for the suggestions guys. I was rather hoping for something more
lightweight than Valgrind - last time I tried it (OK a couple of years ago) I
had horrendous problems - any form of stability even at 4096 frames was
debateable.

However I'm pleased to say running it today with the arguments suggested by
Mark was rather different (although I did have to run at 1024 frames to get the
Xruns down to a few handfulls). It's going to take me some time to work out how
to interpret them results though :(

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