Christoph Lameter wrote:

For Itanium (and I guess also for ppc64 and sparch64) the performance of 
write_lock/unlock is the same as spin_lock/unlock. There is at least 
one case where concurrent reads would be allowed without this patch. 

Yep, I picked up another one that was easy to make lockless (I'll send
out a new patchset soon), however the tagged lookup that was under read
lock is changed to a spin lock.

It shouldn't be too difficult to make the tag lookups (find_get_pages_tag)
lockless, however I just haven't gotten around to looking at the write
side of the tagging yet.

When that is done, there should be no more read locks at all.

Nick

-- 
SUSE Labs, Novell Inc.

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