Re: [PATCH] sched: change pull_rt_task() to decrease time waitingon runqueue

From: Steven Rostedt
Date: Wed May 18 2011 - 11:20:43 EST


On Wed, 2011-05-18 at 22:54 +0800, Hillf Danton wrote:

> In short, if there are pushable tasks and if there are RQs,
> NOT LIMITED TO our RQ, in lower priority, tasks should be pushed to
> RQs as many as we could.

I understand what you are trying to do. But this change modifies a lot
of assumptions. Please supply test cases that shows how this helps.

Have a look at:

http://lwn.net/Articles/425583/

Where I did a bit of work just to make sure my change to sched_rt.c was
appropriate. Just coming up with scenarios may not be good enough.
Seeing it in practice is worth much more.

For example, you may be making the fast path slower. This may do what
you expect, with a hit in performance. I'm not sure I like that idea.

-- Steve


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