Messages in this thread | | | Date | Wed, 10 Sep 2003 08:22:51 +0200 | From | Mike Galbraith <> | Subject | Re: Priority Inversion in Scheduling |
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At 07:35 AM 9/10/2003, Mike Fedyk wrote: >On Wed, Sep 10, 2003 at 06:42:10AM +0200, Mike Galbraith wrote: > > At 02:23 AM 9/10/2003, Nick Piggin wrote: > > >Hi John, > > >Your mechanism is basically "backboost". Its how you get X to keep a > > >high piroirity, but quite unpredictable. Giving a boost to a process > > >holding a semaphore is an interesting idea, but it doesn't address the > > >X problem. > > > > FWIW, I tried the hardware usage bonus thing, and it does cure the X > > inversion problem (yeah, it's a pretty cheezy way to do it). It also > > cures xmms skips if you can't get to the top without hw usage. I also > > tried a cpu limited backboost from/to tasks associated with hardware, and > > it hasn't run amok... yet ;-) > >Against which scheduler, and when are you going to post the patch?
Against stock test-4, but I'm not going to post it. It's just an experiment to verify that there is another simple way to defeat the X inversion problem (while retaining active list requeue). Also, backboost is a tricky little bugger, and I thought I'd let Nick know that I had some success with this heavily restricted form. (global backboost can be down right evil)
If anyone having inversion or concurrency troubles wants to give it a try for grins, they can drop me a line. My tree tends to morph a lot though, depending on what aspect of scheduling I'm tinkering with at the time. It currently does well at defeating known starvation issues, but I don't like it's priority distribution much (and it's not destined for inclusion, and it's pretty darn ugly, and I'll likely break it all to pieces again soon, and...;).
-Mike
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