[Sheepdog] [PATCH 1/2] add oid_to_vnodes() and obj_to_sheeps() to avoid too much vnodes traverse

[Christoph Hellwig]

These patches should not just help with recovery performance but with
anything looking up objects, so thanks a lot for doing this work.

On Mon, May 14, 2012 at 12:12:35PM +0800, levin li wrote:
> oid_to_vnode() and obj_to_sheep() traverse the vnode list to find the
> target vnode, many times, sheep needs to call these two functions nr_copies
> times, it means we also need to traverse the vnode list nr_copies times,
> it's absolutely a waste, so I add these two functions to make it only
> traverse one time in stead of calling obj_to_sheep()/oid_to_vnode() nr_copies
> time.

Any chance you could simply ckill of obj_to_sheep and oid_to_vnode?

oid_to_vnode already has no caller left after your patch, and
obj_to_sheep only one in collie and two in the recovery code.  Avoiding
duplicate code paths helps maintainance over the long run.

Also is there any benefit to keep hval_to_sheeps separate from
obj_to_sheeps?  Especially if you move the fnv_64a_buf into the
bsearch function it should be a lot cleaner than that.

Either way these functions seem to large to be inlined to me, even
before your changes.  Can we move them into out of lines functions
to get better caching behaviour?  Especially with the many callers that
might actually make a difference.