On Tue, Jan 4, 2011 at 15:58, Dario Faggioli <raistlin@linux.it> wrote:
Suppose a RT task blocks on a PI-mutex, the lock owner will be boosted
to RT and go through a class change in rt_mutex_setprio().
Since now a class change reinitializes the class-specific, if fair and
rt fields are on the same memory space, we need to save the
sched_fair_entity before changing the class to RT and put it again
when going back to the fair class.
Quoting Peter about this:
[ Initially I was thinking not, because the task slept we'll have to
reinsert it in the rb-tree anyway, but upon further consideration
that'll loose the old vruntime setting, which can lead to an unseemly
gain of time in place_entity()'s never backward check failing.
So yes, we'd have to place a copy of the old sched_entity in struct
rt_mutex_waiter, not very hard to do. ]
As a side-note: irc this is one thing i didn't do when i prepared that patches.
Lucas De Marchi
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