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Re: Rev 4033: MDEV-5766 - my_atomic_load does memory writes

To: maria-developers@xxxxxxxxxxxxxxxxxxx
From: Sergei Golubchik <serg@xxxxxxxxxxx>
Date: Mon, 10 Mar 2014 15:17:42 +0100
In-reply-to: <20140307074316.061462C41F0@mail.askmonty.org>
User-agent: Mutt/1.5.22 (2013-10-16)

Hi, Sergey!

On Mar 07, Sergey Vojtovich wrote:
> revno: 4033
> revision-id: svoj@xxxxxxxxxxx-20140307074306-i3l4fllu2rj5pouf
> parent: svoj@xxxxxxxxxxx-20140306121912-i1p8iilpsgc8m4bn
> committer: Sergey Vojtovich <svoj@xxxxxxxxxxx>
> branch nick: 10.0
> timestamp: Fri 2014-03-07 11:43:06 +0400
> message:
>   MDEV-5766 - my_atomic_load does memory writes
>   
>   my_atomic_load() is implemented as __sync_fetch_and_or(var, 0) which
>   writes or-ed value back to var. Memory writes as such have worse
>   performance and scalability than reads.
>   
>   gcc 4.7 and up offers better facility for atomic loads/stores. Use it
>   whenever it is available.

Thanks.
ok to push

Regards,
Sergei