Messages in this thread | | | Date | Wed, 10 Sep 2003 19:28:58 +1000 | From | Nick Piggin <> | Subject | Re: Priority Inversion in Scheduling |
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Mike Galbraith wrote:
> 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...;).
Sounds interesting. I my scheduler doesn't have any inversion or starvation issues that I know of without backboost though. I'd like to know if you find any.
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