Re: Move PinBuffer and UnpinBuffer to atomics

On Thu, Sep 24, 2015 at 6:36 PM, Alexander Korotkov <
a(dot)korotkov(at)postgrespro(dot)ru> wrote:

> On Thu, Sep 24, 2015 at 6:32 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>
>> On 2015-09-15 20:16:10 +0300, YUriy Zhuravlev wrote:
>> > We will be tested.
>>
>> Did you have a chance to run some benchmarks?
>>
>
> Yes, we now have 60 physical cores intel server and we're running
> benchmarks on it.
>

We got a consensus with Andres that we should commit the CAS version first
and look to other optimizations.
Refactored version of atomic state patch is attached. The changes are
following:
1) Macros are used for access refcount and usagecount.
2) likely/unlikely were removed. I think introducing of likely/unlikely
should be a separate patch since it touches portability. Also, I didn't see
any performance effect of this.
3) LockBufHdr returns the state after taking lock. Without using atomic
increments it still can save some loops on skip atomic value reading.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company