[CM] file ops
Kjetil Svalastog Matheussen
Fri, 25 May 2007 16:35:12 +0200 (CEST)
On Fri, 25 May 2007, Bill Schottstaedt wrote:
> Since several people seem to be worrying about disk accesses --
> I think that modern OS's (linux in particular)
> automatically cache files in RAM -- what appear to be disk ops are
> actually references to memory. In the bad old days you had to use
> mmap or something -- I forget how it used to work.
> This info itself may be out-of-date -- I am not an OS wizard!
> My first thought when I hear about dropouts is not "disk ops", but
> "garbage collection", and then "X server traffic", and then "some
> background process". I believe the latter is one thing that
> Fernando's real-time kernel deals with. And Motif generates
> at least an order of magnitude less X traffic than Gtk.
> As I say, I don't actually know anything...
Yes, garbage collecting and gtk traffic is what I have found to be the two
largest causes for dropouts in snd as well.
But if the sound processing had been handled in a seperate high priority
thread instead, it would have been possible to increase buffer size
without getting high response time as well, which is what the
<snd-rt-player> instrument does. The <snd-rt-player> instrument does use
some more memory though, but memory is cheap.