Re: [RFC] [PATCH 0/8] Inode diet v2

["Brian F. G. Bidulock" <bidulock@openss7.org>]

Theodore,

On Wed, 21 Jun 2006, Theodore Tso wrote:

> Unfortunately, since these structures are used by a large amount of
> kernel code, some of the patches are quite involved, and/or will
> require a lot of auditing and code review, for "only" 4 or 8 bytes at
> a time (maybe more on 64-bit platforms).  However, since there are
> many, many copies of struct inode all over the kernel, even a small
> reduction in size can have a large beneficial result, and as the old
> Chinese saying goes, a journey of thousand miles begins with a single
> step....

Can you grep inode_cache /proc/slabinfo to see whether you saved any
memory at all?

You need to save 48 bytes per inode to fit one more into a slab with
a 32 byte L1 cache slot; 120 bytes per inode, 64 byte L1 cache slot.
And that's just a generic inode_cache object.  Something that is really
used, like ext3_inode_cache or nfs_inode_cache is going to take more
doing.  Moving a field from the generic inode to the filesystem specific
inode acheives nothing.