Re: [PATCH RFC DRAFT DOESNOTBUILD] inode: free up more space

Christoph Hellwig
2025-07-17T07:51:28Z

On Thu, Jul 17, 2025 at 09:48:49AM +0200, Christian Brauner wrote:
> On Wed, Jul 16, 2025 at 03:02:00PM +0200, Christoph Hellwig wrote:
> > On Tue, Jul 15, 2025 at 05:09:03PM +0100, Matthew Wilcox wrote:
> > > will be harder, we have to get to 604 bytes. Although for my system if
> > > we could get xfs_inode down from 1024 bytes to 992, that'd save me much
> > > more memory ;-)
> >
> > There's some relatively low hanging fruit there.
> >
> > One would be to make the VFS inode i_ino a u64 finally so that XFS
> > and other modern files systems an stop having their own duplicate of
>
> That's already on my TODO since we discussed this with Jeff last year.

Cool!

Btw, I remember anothing I've been wanting to look at, which is
killing the u/g/p quota pointers. If we used a rhashtable with
proper sizing for them, doing a hash lookup instead of the caching
should be efficient enough to be noise compared to the actual quota
operations. That would free three pointers per inode, or in case
of XFS six without the optimization in this thread.
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