Re: [PATCH 5/6] eventfs: get rid of dentry pointers without refcounts

Linus Torvalds
2024-01-30T23:06:32Z

On Tue, 30 Jan 2024 at 14:56, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> With that, the base size of 'struct eventfs_inode' actually becomes 96
> bytes for me.

It can be shrunk some more.

The field ordering is suboptimal. Pointers are 8 bytes and 8-byte
aligned, but 'struct kref' is just 4 bytes, and 'struct eventfs_attr'
is 12 bytes and 4-byte aligned.

So if you pack all the 8-byte-aligned fields at the beginning, and the
4-byte-aligned ones at the end, you get 88 bytes.

At which point a name pointer would *just* fit in 96 bytes.

... and then some debug option is enabled, and it all goes to hell again.

Linus