[gst-devel] pulsesink optimizations

Lennart Poettering lennart at poettering.net
Fri Oct 16 03:47:38 CEST 2009

On Wed, 14.10.09 18:13, pl bossart (bossart.nospam at gmail.com) wrote:

> Howdy Rene',
> > Wim just committed my patch that changes pulsesink back to set the minreq to
> > the value of the latency-time property, which lets applications tune the
> > gst<->pa overhead again.
> Humm, my experiments show that the core activity increases when minreq
> is > 64k. I sort of remember Lennart mentioning that this was the size
> of the block allocated in PA, and beyond this you would use
> malloc().

Yes that is true (as mentioned in my response i sent 5min ago. I
probably should have read the full thread before responding...)

Story goes like this:

If you call pa_stream_write() with memory blocks < 64k, then PA will
be able to place your entire data in a single SHM tile, and is then
able to send the whole thing in one step to the other side. If you
pick larger sizes, then PA cannot optimize things that way and might
end up sending the data via the socket instead of shm.


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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