Re: less expensive pg_buffercache on big shmem

On Fri, Sep 2, 2016 at 8:49 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2016-09-02 08:31:42 +0530, Robert Haas wrote:
>> I wonder whether we ought to just switch from the consistent method to
>> the semiconsistent method and call it good.
>
> +1. I think, before long, we're going to have to switch away from having
> locks & partitions in the first place. So I don't see a problem relaxing
> this. It's not like that consistency really buys you anything... I'd
> even consider not using any locks.

I think we certainly want to lock the buffer header, because otherwise
we might get a torn read of the buffer tag, which doesn't seem good.
But it's not obvious to me that there's any point in taking the lock
on the buffer mapping partition; I'm thinking that doesn't really do
anything unless we lock them all, and we all seem to agree that's
going too far.

--
Robert Haas
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