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Re: More thread scheduling observations
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Re: More thread scheduling observations


  • Subject: Re: More thread scheduling observations
  • From: Andy Bull <email@hidden>
  • Date: Mon, 6 May 2002 01:32:55 +0100

On Sunday, May 5, 2002, at 10:32 pm, Bill Stewart wrote:

One misconception to clear up
There is NO such thing as a low priority RT thread. There is one and only
one priority for a thread with time constraints and that is 96.

ok, perhaps I should have used "importance" instead of "priority" ?


If you do a:
ps -axM
From the terminal (with the optional -p <PID>) you'll see that you're rt
thread is given a priority of 96.

I'd already spotted that this afternoon and was about to post a query ...


Creating 96 threads is in most cases a bad idea to do these kinds of
activities, when in many cases a fixed-priority thread will be more than
sufficient
More to come...

Using a fixed priority thread would be sufficient if there were no dropouts when you move windows etc, but you mentioned a bug in 10.1?
fixed in Jaguar? Does "more to come" mean we're about to get some official documentation/examples ?

ps seems to suggest quicktime uses "96" threads fairly liberally during playback and even when idle. So when is it allowable to use a high priority ? what are the rules when we need reliable low latency? I'm looking forward to getting past this stage my code and being able to feel comfortable in the knowledge that it's done properly.

Bill, I would dearly love to see how you would set up a feeder thread with no dropouts, could you post a few lines of example source? (I guess we have to wait until after WWDC). So far the posts from Kurt and Ian have been most enlightening, and, the only source of enlightenment I've come across outside of deep and heavy unix manuals, mach documentation and Darwin source. What I would like to see from Apple would be a neat, short document that says "this is how we recommend you do it ...", until then I've got to be tempted to stick with a ridiculously high priority (not recommended) thread that seems to work.

I could rant on about this but I'm holding back my frustration in the knowledge that there seems to be many in the same boat ;)
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 >Re: More thread scheduling observations (From: Bill Stewart <email@hidden>)

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