On Sun, 15 Mar 2015, Harry van Haaren wrote:
On Sun, Mar 15, 2015 at 8:29 AM, Jeremy Jongepier <jeremy@xxxxxxxxxxxxxx> wrote:
Which disk writes? From the audio software? Aren't those performed in
the audio thread and if so don't they inherit the higher rtprio assigned
by JACK?
Nope, the audio data is copied into a ringbuffer, and then written to
disk using a non-RT thread.
The write() function call has unbounded execution time, so it must not
be called in the RT thread in order to avoid Xruns.
That was my thought too, SW writes to memory buffers and then the OS
writes the buffers to disk. Though it sounds like you are suggesting there
is yet another layer before the data even makes it to memory buffers.
The reason I asked, is from reading about people using three drives for
audio: OS, sample data, and audio streaming (record). And though I have
not had any problems with disk writes (even when I was using only 1GB of
ram and a PATA drive) I do tend to simpler things of fewer tracks and no
synth. For the most part, I would think any OS parts would be sitting in
memory anyway.
I know there are other applications that run several disks
together using only the outer half tracks in a raid 0 (I think) setup for
faster disk writes, but even there I would think the disk writes are still
much slower than ram.
--
Len Ovens
www.ovenwerks.net
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