Re: uvm_object::vmobjlock

[Antti Kantee <pooka%cs.hut.fi@localhost>]

On Fri Jan 29 2010 at 02:03:23 +0000, Mindaugas Rasiukevicius wrote:
> > If you are talking about memory not within the object, well, then "all
> > bets are off" applies.  I might argue equally handwavily that you'll
> > cause false sharing with other locks from the mutex obj pool, and even
> > for many many more locks, since you don't even get the "protection" of
> > the data after the lock being "safe". <...>
> 
> Heh?  The mutex object pool has a necessary alignment and padding, which
> guarantees that the lock has its own cache line.  That was one of the
> reasons, besides reference counting, why lock object pool was invented.

Ooops.  I meant to handwave about how you're now wasting multiple cache
lines where previously only one pretty much always uncontended line
was required.  I'm not convinced at all this is improving performance.
Anyway, you get the point.