| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Reduce ProcArrayLock contention |
| Date: | 2015-08-04 16:11:02 |
| Message-ID: | CA+TgmoaLL7R50Fc-J8Ez301anCyOtLO56GN2cqnoSnZ2wMYAxQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Aug 4, 2015 at 11:50 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> I have kept barriers based on comments on top of atomic read, refer
> below code:
>
> * No barrier semantics.
> */
> STATIC_IF_INLINE uint32
> pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
>
> Note - The function header comments on pg_atomic_read_u32 and
> corresponding write call seems to be reversed, but that is something
> separate.
That doesn't matter, because the compare-and-exchange *is* a barrier.
Putting a barrier between a store and an operation that is already a
barrier doesn't do anything useful.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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