Re: Move PinBuffer and UnpinBuffer to atomics

On Tuesday 15 September 2015 16:50:44 Andres Freund wrote:
> No, they can't in a a relevant manner. We hold the buffer header lock.
I'm sorry, I did not notice of a LockBufHdr.

In this embodiment, your approach seems to be very similar to s_lock. Cycle in 
PinBuffer behaves like s_lock.
In LockBufHdr:
if (pg_atomic_compare_exchange_u32(&desc->state, &state, state | BM_LOCKED))

conflict with:
while (unlikely(state & BM_LOCKED))
from PinBuffer.
Thus your patch does not remove the problem of competition for PinBuffer.
We will try check your patch this week.

>You're posting
>things for review and you seem completely unwilling to actually respond
>to points raised.
I think we're just talking about different things.
-- 
YUriy Zhuravlev
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