Re: [PATCH 3/6] fs: Introduce a per_cpu last_ino allocator

[Christoph Hellwig]

On Thu, Nov 27, 2008 at 12:32:24AM +0100, Eric Dumazet wrote:
> new_inode() dirties a contended cache line to get inode numbers.
>
> Solve this problem by providing to each cpu a per_cpu variable,
> feeded by the shared last_ino, but once every 1024 allocations.
>
> This reduce contention on the shared last_ino.
>
> Note : last_ino_get() method must be called with preemption
> disabled on SMP.

Looks a little clumsy.  One idea might be to have a special slab for
synthetic inodes using new_inode and only assign it on the first
allocation and after that re-use it.

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