Re: dentry bloat.
From: Andrew Morton
Date: Sat May 08 2004 - 05:43:17 EST
> On Sat, May 08, 2004 at 03:11:59AM -0700, Andrew Morton wrote:
> > Andrew Morton <akpm@xxxxxxxx> wrote:
> > >
> > > Here be another patch.
> > Can't help myself!
> > - d_vfs_flags can be removed - just use d_flags. It looks like someone
> > added d_vfs_flags with the intent of doing bitops on it, but all
> > modifications are under dcache_lock. 4 bytes saved.
> Bzzert. ->d_vfs_flags modifications are under dcache_lock; ->d_flags ones
> are *not* - they are up to whatever filesystem code happens to use them.
yup, I hunted down the rest.
> > - Pack things so that dentry.d_name.len and dentry.d_flags occupy the same
> > word. 4 bytes saved.
> d_name.len is accessed on very hot paths. In particular, we are looking
> at it while traversing hash chains and we do that without dcache_lock
> (see callers of ->d_compare()).
That's OK. The d_move() d_movecount and locking logic takes care of that.
But the ushorts are a bit dopey - I'll give those 4 bytes back.
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