Hi Sergey,

I looked into fast mutex in the past [1] and was never able to get a straight answer (even from the original developer) on what was the intention behind it and how it made things faster as it actually made things slower in the past (Bug#38941, others). There is a comment in http://bugs.mysql.com/bug.php?id=58766 highlighting one case where I saw a small performance improvement, but even that was highly workload/hardware dependent (can't recall which workload exactly, might have been sysbench's point select or something similar).

1. http://dev.mysql.com/worklog/task/?id=4601

On Wed, Feb 26, 2014 at 10:36 PM, Sergey Vojtovich <svoj@mariadb.org> wrote:

Hi Sergei,

do you know if we ship any binaries with fast mutex (-DMY_PTHREAD_FASTMUTEX)
enabled or officially suggest it? What was it's intention and what loads it was
supposed to make faster?

I'm trying to understand if fastmutex is worth fixing. It looks like duplication
of PTHREAD_MUTEX_ADAPTIVE_NP, so we have double spinning when they're enabled.
According to my recent benchmarks it shown worst performance.

Thanks,
Sergey

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