Re: Our "fallback" atomics implementation doesn't actually work

From: Andres Freund <andres(at)anarazel(dot)de>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: Our "fallback" atomics implementation doesn't actually work
Date: 2016-10-05 18:13:29
Message-ID: 20161005181328.x463t4wwg2tdep7p@alap3.anarazel.de
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On 2016-10-05 14:01:05 -0400, Tom Lane wrote:
> I was trying to measure whether unnamed POSIX semaphores are any faster
> or slower than the SysV kind. Plain pgbench is not very helpful for
> determining this, because we've optimized the system to the point that
> you don't hit semop waits all that often. So I tried this:
>
> configure USE_UNNAMED_POSIX_SEMAPHORES=1 --disable-cassert --disable-spinlocks --disable-atomics

Pretty independent from the complaint at hand, but if I just do that I get
undefined reference to symbol 'sem_post@@GLIBC_2.2.5'

I needed to add -pthread -lrt to LDFLAGS to make it work.

Andres

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