sched_4BSD

[Sarath Kamisetty]

Hi,

How does Linux handle this ? Any idea ?

Thanks,
Sarat

On Mon, 28 Feb 2005 00:26:10 -0800, Julian Elischer <julian at 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
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