cvs commit: src/sys/vm vm_map.c vm_map.h

[Stephan Uphoff]

John Baldwin wrote:
> On Friday 30 July 2004 12:06 pm, Brian Fundakowski Feldman wrote:
> > On Fri, Jul 30, 2004 at 09:10:28AM +0000, Maxime Henrion wrote:
> > > mux         2004-07-30 09:10:28 UTC
> > >
> > >   FreeBSD src repository
> > >
> > >   Modified files:
> > >     sys/vm               vm_map.c vm_map.h
> > >   Log:
> > >   Get rid of another lockmgr(9) consumer by using sx locks for the user
> > >   maps.  We always acquire the sx lock exclusively here, but we can't
> > >   use a mutex because we want to be able to sleep while holding the
> > >   lock.  This is completely equivalent to what we were doing with the
> > >   lockmgr(9) locks before.
> >
> > Not that I don't think it's worth doing in general, but is there a
> > comparison anyone has done between speeds of sx and lockmgr?
> 
> Speed aside, when allproc_lock and proctree_lock were lockmgr locks (before sx 
> was implemented), my SMP machines routinely locked up and when I looked at 
> things in the debugger it seemed that no one held allproc_lock but several 
> processes were blocked on it.  Quite frankly, I don't trust lockmgr()'s 
> implementation.
> 

Since the vfs layer forces me to use the lockmgr you scared me into 
taking a look.
And yes there is a bug in the current implementation. (kern/69934).

	Stephan