[dm-devel] [PATCH 4/5] aio: vmap ringbuffer
Zach Brown
zab at redhat.com
Tue Oct 9 22:58:36 UTC 2012
> Not if we decouple the ringbuffer size from max_requests.
Hmm, interesting.
> This would be useful to do anyways because right now, allocating a kiocb
> has to take a global refcount and check head and tail in the ringbuffer
> just so it can avoid overflowing the ringbuffer.
I'm not sure what you mean by a 'global refcount'.. do you mean the
per-mm ctx_lock?
> If we change aio_complete() so that if the ringbuffer is full then the
> kiocb just goes on a linked list - we can size the ringbuffer so this
> doesn't happen normally and avoid the global synchronization in the fast
> path.
How would completion events make their way from the list to the ring if
an app is only checking the ring for completions from userspace?
- z
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