[haiku-development] Re: Scheduler algorithm improvements
- From: "Axel Dörfler" <axeld@xxxxxxxxxxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Mon, 09 Nov 2009 16:32:41 +0100
Mikhail Panasyuk <otoko@xxxxxxxxx> wrote:
> There is something wrong with the way you, Haiku developers, define
> priorities
> for some system services and apps. Critical for overall performance
> and
> responsiveness threads many other threads depend on have too low
> priorities.
You're actually right here: the reason is that the normal thread
priority is indeed used for CPU heavy tasks. An application developer
should normally choose B_LOW_PRIORITY for those, but I guess we
shouldn't rely on that, especially with CLI apps.
IOW it makes sense to elevate the priority of important system threads;
I've now done so in r33961.
An alternative approach would be to automatically give worker threads a
lower priority.
> + most other kernel_team threads with 10 priority in case there are
> _lots_ of
> 10-priority tasks (see PS. section for details why)
I haven't changed those yet; some needs a bit more thinking.
> - MediaPlayer:
> 1. media extractor thread
> 2. event queue runner
> 3. playback manager
I haven't changed those either, since I guess Stippi (or someone else)
will have a better understanding about which thread should get a higher
priority and why.
> - input_server:
> 1. input_server
> Give it at least 11 if you want fast menus' and buttons' interaction
> with mouse
> and redraw.
That one was indeed much too low, although the description doesn't
really fit, as the complete event queue was separated from that one.
> - Tracker:
> 1. Tracker
>
> At least 11 if you want fast Desktop redraw and FS-navigation. Slow
> desktop
> redraw affects MediaPlayer.
Hardly imaginable - looking at what the Tracker thread does, it's almost
nothing.
> - app_server:
> 1. picasso
> 2. screen manager
Those two don't really do a lot, but you're right, giving them a higher
priority doesn't hurt either.
> There is one important thing about BeOS/Haiku schedulers every
> developer
> must know.
[...]
Indeed, but that's also mostly neglectable because Haiku is no server
OS - you just won't have dozens of worker threads running all day.
Bye,
Axel.
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