Re: Configure template change to use SysV Semaphors on darwin

From: "Takayuki Tsunakawa" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com>
To: "Chris Marcellino" <cmarcellino(at)apple(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-patches(at)postgresql(dot)org>
Subject: Re: Configure template change to use SysV Semaphors on darwin
Date: 2007-02-08 06:40:32
Message-ID: 016601c74b4c$07f45800$19527c0a@OPERAO
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From: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> Probably not. The issues about Darwin's POSIX-sema implementation
> are (a) eating backend open-file slots, which won't matter when a
> backend only touches a few different tables as pgbench does; and
> (b) extra process-launch overhead, which won't matter to pgbench
> because it's not launching new backends throughout the test.

About (b), pgbench -C (upper case) can do.

> I'm not sure that there is any standardized test that measures
> these things, and yet it seems like it oughta matter in the real
> world ...

Does POSIX sema implementation use fds on popular platforms like
Linux? Even if so, the users are freed from many kernel parameters
such as semmni, semmns, semmsl, etc. What the users have to care
about becomes only the number of file descriptors. Doesn't it seem to
make settings easy?

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