RE: [Boost-Users] set thread priority

From: William E. Kempf (wekempf_at_[hidden])
Date: 2002-11-05 13:56:02

Mark Storer said:
> I'd think you could get away with something like a set range, like 0 to
> 1000, and then map those values into whatever system is present.  You
> could even use floating point values, 0.0 to 1.0, though people might
> look at you cross-eyed, at least until they got used to the idea.  Then
> it's just a matter of mapping those ranges to whatever OS settings are
> present.
>
> You just state up front a couple caveats:  Given two threads, A (higher
> priority) and B (lower priority), you only guarentee that A won't be
> given a lower underlying system priority than B.  This would save you
> quite a bit of grief... particularly when someone wants threads with
> priority 1.0, 0.99 and 0.98.  The thread with 0.98 might not run slower
> than the one with a 1.0 priority, but it certainly won't be faster.
>
> SOUNDS simple enough.  At least to someone whose sum total
> multi-threading experience is a toy java applet and a dozen lines of
> boost::thread code.  ;)

Some of the issues:

* Min and Max values for priorities are platform specific.  Not all
platforms provide a means to determine these values.

* Priorities are directly related to policies.  You can't implement
priorities with out addressing policies.

* The Min and Max values on a single platform can vary by policy.

* Some policies require other configurable settings.

You get the idea.  It's all very doable, but as usual it's more difficult
than it at first appears.  I've got a general design written up and just
have to tackle implementing it.

-- 
William E. Kempf