[Haskell-cafe] Precise timing

[Carter Schonwald]

to clarify, the -C flag is an RTS flag

On Sun, Oct 19, 2014 at 12:48 AM, Carter Schonwald <
carter.schonwald at gmail.com> wrote:

> if you care about precise timing (at the cost of of some loss of
> throughput)
> you can compile your code with -fno-omit-yields, and also the context
> switching timer
> see eg
> http://www.haskell.org/ghc/docs/7.4.2/html/users_guide/using-concurrent.html
>
> default context switching rate for threads is -C0.02 (20ms), but you can
> set the rate as small as you like, and -C0 will trigger a context switch at
> every yield.
>
> happy experimenting!
>
> On Sat, Oct 18, 2014 at 10:19 PM, Brandon Allbery <allbery.b at gmail.com>
> wrote:
>
>> On Sat, Oct 18, 2014 at 9:36 PM, Jeffrey Brown <jeffbrown.the at gmail.com>
>> wrote:
>>
>>> threadDelay is guaranteed
>>> <http://hackage.haskell.org/package/base-4.7.0.1/docs/Control-Concurrent.html#v:threadDelay>
>>>
>>>  to wait at least as long, but potentially longer than, what the caller
>>> specifies. Another potential problem could be buffering in printf.
>>> (Eventually I intend to replace the printf statement with OSC output to a
>>> sound generator.)
>>>
>>
>> This isn't going to be solved completely within Haskell; the behavior of
>> threadDelay is the behavior of the system scheduler for a normal process,
>> possibly modified by garbage collection delays. You'll need to switch the
>> process to a realtime scheduling class to remove --- or at least reduce ---
>> the OS's contribution to the uncertainties in sleep times.
>>
>> --
>> 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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>>
>
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