HID and threads WAS: [PD-dev] audio interruptions from outside events (only with Pd)
Tim Blechmann
tim at klingt.org
Mon Dec 4 21:19:18 CET 2006
On Mon, 2006-12-04 at 14:53 -0500, Hans-Christoph Steiner wrote:
>
> > I have no idea about the inner workings of hidio (is there a
> > separate low-priority thread for handling the HID requests?)
>
> This was bugging me so I have to respond to it. From what I've
> seen,
> I think handling HID I/O in a low priority thread would be a bad
> idea. Do you know any application that does that? The effect would
> be that your mouse pointer would skip whenever something with higher
> priority was run. This may be the case on Windows, but definitely
> not on Mac OS X and GNU/Linux.
>
> On Mac OS X, the kernel queues HID events and uses wired kernel
> memory for the queues to ensure that those events get out there as
> soon as possible and reliably without a thread. No example code
> that
> I have seen, from Apple or others, puts HID event handling in a
> thread. To put it simply: you don't want your mouse pointer to be
> pre-empted.
well, it depends on how you can query the hid i/o. if the access to the
hid backend is either blocking or slow, you should think about putting
the specific code in a thread with a lower priority than the audio
thread, unless you prefer a smooth mouse movement over audio dropouts :)
imo, all non-audio i/o of a low-latency system should should be detached
from the audio thread to avoid dropouts.
tim
--
tim at klingt.org ICQ: 96771783
http://www.mokabar.tk
All we composers really have to work with is time and sound - and
sometimes I'm not even sure about sound.
Morton Feldman
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: This is a digitally signed message part
URL: <http://lists.puredata.info/pipermail/pd-dev/attachments/20061204/c58b720e/attachment.pgp>
More information about the Pd-dev
mailing list