Sorry I wish I was part of the development effort. I am just coming on board with FreeBSD work.
I guess ksegrps were implemented for the purpose of PROCESS_SCOPE threads and like you said avoiding a process from hogging the CPU. If every thread in the system has it's own ksegrp (SYSTEM_SCOPE) I don't see this call (maybe_preempt_in_ksegrp) ever getting called :). Thanks ravi -----Original Message----- From: Julian Elischer [mailto:[EMAIL PROTECTED] Sent: Wednesday, April 30, 2008 3:52 PM To: Murty, Ravi Cc: [email protected] Subject: Re: maybe_preempt_in_ksegrp Murty, Ravi wrote: > Julian, > > Apologies for sticking to 6.x, I checked and looks like this function > and several others are out in 7.x. It's just that we've been using 6.x > for a while and continue to look at it. :) > > > Coming back, I was thinking of the problem the other way around. The > thread gets put on the ksegrp runq, but we don't know if it gets put at > the head of the queue. All we know is we either find a slot or not. If > we do, great sched_add is called which will add it to a CPU runq and > check if it can preempt some thread on the target CPU. If we can't find > a slot, it checks if it can steal (preempt) some other thread (of the > same ksegrp) from a cpu. Let's consider the UP case to keep this simple. > One of the checks is the priority of the newly runnable thread and the > curthread on the CPU and the fact that they are part of the same KSEGRP. > If both pass, I think it should say "run me" since we just established > that I am higher priority than what's running on the CPU. > > Ravi > Quite possibly.. where were you when we needed more man-power on this :-) this was part of the attempt to make a 'fair' scheduler which would not gove a person 10,000 times the cpu just because he had 10000 threads :-) It was eventually removed as being too complicated, too resource intensive, and not solving a problem that people were seeing. _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
