Re: [patch][rfc] fs: shrink struct dentry

On Mon, Dec 01, 2008 at 05:51:13PM +0000, John Levon wrote:
> On Mon, Dec 01, 2008 at 09:33:43AM +0100, Nick Piggin wrote:
> 
> > I then got rid of the d_cookie pointer. This shrinks it to 192 bytes. Rant:
> > why was this ever a good idea? The cookie system should increase its hash
> > size or use a tree or something if lookups are a problem.
> 
> Are you saying you've made this change without even testing its
> performance impact?

For oprofile case (maybe if you are profiling hundreds of vmas and
overflow the 4096 byte hash table), no. That case is uncommon and
must be fixed in the dcookie code (as I said, trivial with changing
data structure). I don't want this pointer in struct dentry
regardless of a possible tiny benefit for oprofile.

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