Re: dentry bloat.

[Matt Mackall <mpm@selenic.com>]

On Mon, May 10, 2004 at 02:46:58AM -0700, Andrew Morton wrote:
> Arjan van de Ven <arjanv@redhat.com> wrote:
> >
> > On Mon, 2004-05-10 at 10:27, Helge Hafting wrote:
> >  > Matt Mackall wrote:
> >  > 
> >  > >One also wonders about whether all the RCU stuff is needed on UP. I'm
> >  > >not sure if I grok all the finepoints here, but it looks like the
> >  > >answer is no and that we can make struct_rcu head empty and have
> >  > >call_rcu fall directly through to the callback. This would save
> >  > >something like 16-32 bytes (32/64bit), not to mention a bunch of
> >  > >dinking around with lists and whatnot.
> >  > >
> >  > >So what am I missing?
> >  > >  
> >  > >
> >  > Preempt can happen anytime, I believe.
> > 
> >  ok so for UP-non-preempt we can still get those 16 bytes back from the
> >  dentry....
> 
> I suppose so.  And on small SMP, really.  We chose not to play those games
> early on so the code got the best testing coverage.

Ok, I can spin something up. I'll start with a generic no-RCU-on-UP
and then we can think about the small SMP case a bit later.

-- 
Matt Mackall : http://www.selenic.com : Linux development and consulting