Hi, Andres!
On Fri, Nov 4, 2022 at 10:07 PM Andres Freund <andres@anarazel.de> wrote:
> The use of cmpxchg vs lock inc/lock add/xadd is one of the major reasons why
> lwlocks are slower than a spinlock (but obviously are better under contention
> nonetheless).
>
>
> I have a benchmark program that starts a thread for each physical core and
> just increments a counter on an atomic value.
Thank you for this insight! I didn't know xadd is much cheaper than
cmpxchg unless there are retries. I also wonder how cmpxchg becomes
faster with higher concurrency.
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Regards,
Alexander Korotkov