16 mutext lock/unlocks per query?

[Rick Jones]

Paul A Vixie wrote:
> 
> > Which platforms are considered as having lightweight mutexes?
> 
> bsd is what we had in our hands at the time we did the design.

Sadly, I have no such box in my stable to profile...

> it simply never occurred to us that there would ever be a thread
> implementation without inline functions and without usermode TSI
> before syscall.

I cannot say whether or not the HP-UX pthread mutext calls are
"lightweight" or "heavyweight" and the term TSI is not resonating in my
head, but I do know that under HP-UX, the pthread_mutex_lock and
pthread_mutex_unlock calls will do their thing entirely in user-space
unless there is contention for the mutex. When there is contention, you
may start to see calls to sched_yield() and possibly ksleep and then
kwakeup. 

The profile should show the syscall stubs for when those things were
called. As I recall, that was rather rare.

rick jones
-- 
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