On Sat, 12 Jun 1999, John S. Dyson wrote:
> Soren Schmidt said:
> [Charset ISO-8859-1 unsupported, filtering to ASCII...]
> > It seems Christopher R. Bowman wrote:
> > [exelent explanation snipped]
> > > The alternative to the Giant Kernel Lock(tm) is so called fine grained
> > > locking
> > > wherein locking is pushed down closer to the data structures. In fine
> > > grained
> > > locking two processors might be executing in the kernel at the same time,
> > > but
> > > only if they didn't need the same resources. On might be doing a disk
> > > read
> > > while the other queues up a character for the serial port. The fine
> > > grained
> > > lock has the potential for higher parallelism and thus better throughput
> > > since
> > > process may not have to wait as long, but the larger number of locks with
> > > their
> > > many required lock and unlock operations add overhead and further the
> > > design is
> > > more difficult and error prone since the interaction of the numerous
> > > locks may
> > > result in deadlock or livelock situations every bit as problematical as
> > > the
> > > problem they try to solve.
> >
> > There are also those of us that dont belive in finegrained locking, exactly
> > because of all the small locks you have to check/lock/open, the overhead is
> > not worth it.
> >
> Finegrained locking either requires developers with IQ's of 200 or higher,
> or a different kernel structure. I suggest that finegrained locking is cool,
> and can be intelligently used to mitigate (but not solve) the effects of
> lots of problems -- however, it would be unwise to embark on an effort to make
> the FreeBSD kernel into an efficent 16way SMP kernel by using finegrained
> locking all over the place.
But your microkernel-hybrid BSD will do 16way SMP with a fully-parallelized
kernel?
>
> --
> John | Never try to teach a pig to sing,
> dy...@iquest.net | it makes one look stupid
> jdy...@nc.com | and it irritates the pig.
>
>
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