Signals and preemption-related question

Hi,

Michael and I were having a discussion about the current behavior with
respect to preemption on release_sem_etc and/or signal delivery, and
an uncertain question crops up: In quite a few cases, if a thread is
woken up by either one, that wakeup is being used as a communications
mechanism between two threads (i.e. to wake up another thread and tell
it data is ready to be worked on). However, the scheduler currently
only preempts if the new thread's priority is greater than that of the
instigator. In cases like this though, it's entirely possible the two
threads will be of equal priority, and as such that strategy might
result in undesired latency on waking up the recipient since the
sender will be allowed the rest of its timeslice. However, at the same
time, if we did signal preemption on equal priority, there's still no
guarantee that the target thread will in fact be the one woken up due
to a) the 20% random factor we use for priority skipping, and b) the
fact that we enqueue new threads at the end of the list of waiting
threads at the same priority, and as such if another is waiting it
will go first (if it goes at all). Is this a situation we want to deal
with, and if so, any thoughts on how?

Regards,

Rene

------------------------------------------------------------------------------
Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day 
trial. Simplify your report design, integration and deployment - and focus on 
what you do best, core application coding. Discover what's new with 
Crystal Reports now.  http://p.sf.net/sfu/bobj-july