[gst-devel] mini filesrc patch

vishnu at pobox.com vishnu at pobox.com
Mon Oct 1 13:24:10 CEST 2001

On Mon, Oct 01, 2001 at 12:55:05PM -0700, Erik Walthinsen wrote:
> On Sun, 30 Sep 2001 vishnu at pobox.com wrote:
> > i don't understand why touch is currently set to TRUE.
> > -  src->touch = TRUE;
> > +  src->touch = FALSE;
> The touch param causes filesrc to read a word at the beginning of each
> page.  This forces the kernel to read the data from the disk into
> bufcache.

Yah ..,

> The reason this is necessary and on by default is that without
> it, the first element to touch the data has to wait for the data to come
> off disk.  In a bandwidth/latency critical situation, you'll have a thread
> containing the filesrc and one or more threads containing the rest of the
> pipeline.  The goal of this is to use the filesrc thread to manage the
> disk I/O, which when using mmap means touching the data, which isolates
> the latencies of doing so in their own thread, behind a queue that can
> help absorb them.

OK, but i'm not convinced that this is *always* the right thing to do.

Will you accept a patch to make 'touch' a gobject property?

Victory to the Divine Mother!!

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