(no subject)

From: k.hagan_at_[hidden]
Date: 2001-09-10 11:57:18

Bill Kempf wrote...

> This [http://world.std.com/~jmhart/csmutx.htm] was the article
> that someone pointed me to.  The conclusion was that CS are only
> faster if:
>
> * There are less than 8 threads total in the process.
> * You weren't running in the background.
> * You weren't on an dual processor machine.

That's not how I read it. The test program used in this paper
does nothing else but bang on 1 or 2 critical sections. That
surely isn't realistic. Most programs don't have 8 threads that
have nothing better to do in life than torture a single CS.

Entering a CS is one or two instructions unless the section is
already held, in which case it is a wait on a mutex. Waiting on
a mutex involves a kernel switch. OK, so someone has written a
benchmark that shows the mutex winning. Am I the only person who
thinks the benchmark might be suspect?