[Haskell-cafe] Precise timing

[Jeffrey Brown]

Again thank you to everybody!

Brandon, I see no warnings in the documentation regarding privilege
requirement for raising a scheduler's priority -- the strings "priv" and
"user" are absent, and "su" only appears twice. Also I did not understand
until today that while Mac is a variety of Unix, it is not a variety
of Linux.

Carter and John, I will try the polling method you suggest. A polling cycle
with a period of 20 ms would be fast enough for me. I don't need Haskell to
handle audio math, just to send control signals (to Max/MSP). As soon as I
figure out how to get UDP from Haskell to Max, I'll run a test. Hopefully
the problem I'm seeing derives from print, not threadDelay. (threadDelay
accepts its time argument in millionths of a second! That would seem
to suggest it was designed to handle at least the speed I'm hoping for ...)

On Sun, Oct 19, 2014 at 2:11 PM, Brandon Allbery <allbery.b at gmail.com>
wrote:

> On Sun, Oct 19, 2014 at 3:44 PM, Jeffrey Brown <jeffbrown.the at gmail.com>
> wrote:
>
>> You mean I should call chrt from the command line after starting the
>> process, to modify its priority?
>>
>
> Normally you'd use it to run the program. But, as I said at least twice,
> it's Linux specific.
>
>
>> This documentation
>> <http://hackage.haskell.org/package/posix-realtime-0.0.0.1/src/System/Posix/Realtime/RTSched.hsc> for
>> the posix-realtime package
>> <https://hackage.haskell.org/package/posix-realtime> says that it has a
>> sched_setscheduler function. That supposedly exists on my OS (OS X 10.9).
>> The chrt command, on the other hand,
>>
>
> Does it warn you that you need privileges (probably root) to switch to a
> higher scheduler level? Normally realtime and other high priority
> schedulers require elevated privileges, whereas lower priority schedulers
> such as SCHED_IDLE don't.
>
> I should note that I see no manpage for sched_setscheduler on 10.9.5, nor
> do I find it in any of the dylibs in /usr/lib.
>
> --
> brandon s allbery kf8nh                               sine nomine
> associates
> allbery.b at gmail.com
> ballbery at sinenomine.net
> unix, openafs, kerberos, infrastructure, xmonad
> http://sinenomine.net
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/haskell-cafe/attachments/20141019/a1169ffb/attachment-0001.html>