[Haskell-cafe] Precise timing

[Carter Schonwald]

I think threadDelay is the wrong operation here. Its fundamentally a
primitive for **spreading out** compute, rather than *scheduling compute*.
one (crazy) idea might be the following, say you wanna do an event every X
milli seconds (with some error tolerance about the precise timing),
do a threadDelay for  1/2-2/3rds X, then poll the time constantly :)

OTOH, as other folks are suggesting, theres probably fundamentally better
primitives already available.

On Sun, Oct 19, 2014 at 5:11 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
>
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