[gst-devel] strange CPU loading for audiotestsrc and filesrc

Stefan Kost ensonic at hora-obscura.de
Mon Oct 12 22:26:30 CEST 2009

Michael Smith schrieb:
> On Wed, Oct 7, 2009 at 10:49 PM, Viraj Karandikar <virajk at gmail.com> wrote:
>> Hi,
>> I am seeing some strange behaviour while doing CPU load measurement when
>> running gstreamer.
>> I am relying on uptime and idle time give by "cat /proc/uptime" to calculate
>> CPU load.
>> We have implemented custom audio source (dalsrc) and sink (dalsink) plugins
>> for our board (ARM9E on TI DM6446).
>> I am using gstreamer-0.10.24.
>> I have following two cases:
>> Case 1:
>> gst-launch audiotestsrc wave=silence is_live=true blocksize=160 !
>> audio/x-raw-int,rate=8000,depth=16,channels=2,width=16,signed=\(boolean\)TRUE,endianness=\(int\)1234
>> ! dalsink
>> Average CPU load over 5 minutes : 18%
> As well as your cpu usage measurement technique being pretty
> inaccurate, it's not surprising that audiotestsrc is slow - it's a
> test element, and has has absolutely no optimisation done, or even any
> attempt to make it vaguely ok. It's probably just doing something
> stupid for the silence case.

Well, it actually has bben optimized somewhat. Especially for silence it
*shouldn't* do much. But anyway the only way to find out would be to run e.g.
oprofile on it (its available on arm too).

A slightly better version to check the load would imho be to use sync=false on
the sink and run the example with time. Then see which version is finished earlier.


> Additionally, the first case is a live source - your second isn't.
> Those aren't very directly comparable. There might be something that's
> slower because of that.
> Mike
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