Re: [PATCH 15/18] fs: introduce a per-cpu last_ino allocator

Andi Kleen
2010-10-08T08:22:37Z

Dave Chinner <david@fromorbit.com> writes:

> From: Eric Dumazet <eric.dumazet@gmail.com>
>
> new_inode() dirties a contended cache line to get increasing
> inode numbers. This limits performance on workloads that cause
> significant parallel inode allocation.
>
> Solve this problem by using a per_cpu variable fed by the shared
> last_ino in batches of 1024 allocations. This reduces contention on
> the shared last_ino, and give same spreading ino numbers than before
> (i.e. same wraparound after 2^32 allocations).

This doesn't help for Unix disk file systems, so not fully sure why you
need it for XFS.

But looks reasonable, although it would be better to simply fix
sockets/pipes/etc. to not allocate an inode numbers.

Acked-by: Andi Kleen <ak@linux.intel.com>

-Andi

--
ak@linux.intel.com -- Speaking for myself only.