Re: [PATCH] improve jbd fsync batching

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 03 Nov 2008 22:24:28 -0700 Andreas Dilger <adilger@sun.com> wrote:

> On Nov 03, 2008  12:27 -0800, Andrew Morton wrote:
> > On Tue, 28 Oct 2008 16:16:15 -0400
> > Josef Bacik <jbacik@redhat.com> wrote:
> > > +		spin_lock(&journal->j_state_lock);
> > > +		commit_time = journal->j_average_commit_time;
> > > +		spin_unlock(&journal->j_state_lock);
> > 
> > OK, the lock is needed on 32-bit machines, I guess.
> 
> Should we pessimize the 64-bit performance in that case, for 32-bit
> increasingly rare 32-bit platforms?

In general no.

But spinlocks also do memory ordering stuff on both 32- and 64-bit
machines.  Introducing differences there needs thinking about.

In this case it's fsync which is going to be monster slow anyway.