Date: Tue, 1 Mar 2005 11:20:23 -0800 From: Sarath Kamisetty <sarath.kamisetty@gmail.com> To: Julian Elischer <julian@elischer.org> Cc: Ashwin Chandra <ashcs@ucla.edu> Subject: Re: sched_4BSD Message-ID: <641e6aa9050301112016d316bb@mail.gmail.com> In-Reply-To: <4222D5A2.9010301@elischer.org> References: <001a01c51d6d$d50ce500$abe243a4@ash> <4222D5A2.9010301@elischer.org>
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Hi, How does Linux handle this ? Any idea ? Thanks, Sarat On Mon, 28 Feb 2005 00:26:10 -0800, Julian Elischer <julian@elischer.org> wrote: > Ashwin Chandra wrote: > > I wanted to get some clarification about the 4BSD scheduler. I am sort of > > confused why there are two forms of scheduling, one done between processes and > > another done between threads in a process. The priority calculations seem to be > > done only with processes and I assume that the global run queue holds processes, > > not threads. Also why is there only 1 run queue for 1 CPU. What happens to > > blocked processes and ready to be runned processes? > > Part of the challenge of adding threads to a system is to make it hard for a > threaded process to "flood" the system run queues so that other processes > get no cpu time. > > The scheme in the current freeBSD schedulers is a "crude" method, by which > only a limitted number of threads per process are allowed to be added to > the system run queue. RUnnable hreads fo r aprocess are kept on a run queue for > the process and only the highest N prioriy hreads are actually put on the > system run queue. > > This is by no means the best way, but rather the > easiest way. I am hoping that some PhD candidate somewhere will decide > that thread scheduling is his topic and will figure out a better way > of doing this. > > both run queues hold threads. This is still a place wjere a lot > of work can be done. > > :-) > > > > > > Ash > > _______________________________________________ > > freebsd-hackers@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" > > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" >
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