On 12/28/2010 12:54 AM, Mike Galbraith wrote:
On Mon, 2010-12-20 at 17:04 +0100, Mike Galbraith wrote:
On Mon, 2010-12-20 at 10:40 -0500, Rik van Riel wrote:
On 12/17/2010 02:15 AM, Mike Galbraith wrote:
BTW, with this vruntime donation thingy, what prevents a task from
forking off accomplices who do nothing but wait for a wakeup and
yield_to(exploit)?
Even swapping vruntimes in the same cfs_rq is dangerous as hell, because
one party is going backward.
I just realized the answer to this question.
We only give cpu time to tasks that are runnable, but not
currently running. That ensures one task cannot block others
from running by having time yielded to it constantly.
Hm. Don't think that will 100% sure prevent clock stoppage, because the
running task doesn't necessarily advance min_vruntime.
What about something like the below instead? It compiles, but may eat
your first born child.
(either it's christmas, or nobody cares to try it. ho ho hum:)
It's christmas.
I've replaced my original patch with your patch in my
series, just haven't gotten around to running Avi's
latest test on it yet :)
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