From: Christopher Browne <cbbrowne@acm.org>
To: pgsql-performance@postgresql.org
Subject: Re: shared_buffer optimization
Date: Tue, 08 Aug 2006 08:20:01 -0400
Message-ID: <87u04nv2q6.fsf@wolfe.cbbrowne.com> (raw)
References: <44D86A00.90106@rentalia.com>
Quoth ruben@rentalia.com (Ruben Rubio):
> Hi, I have a question with shared_buffer.
>
> Ok, I have a server with 4GB of RAM
> -----
> # cat /proc/meminfo
> MemTotal: 4086484 kB
> [...]
> -----
>
> So, if I want to, for example, shared_buffer to take 3 GB of RAM then
> shared_buffer would be 393216 (3 * 1024 * 1024 / 8)
>
> Postmaster dont start.
> Error: FATAL: shmat(id=360448) failed: Invalid argument
>
>
> I can set a less value, but not higher than 3 GB.
>
> Am I doing something wrong?
> Any idea?
Yes, you're trying to set the value way too high.
The "rule of thumb" is to set shared buffers to the lesser of 10000
and 15% of system memory. In your case, that would be the lesser of
10000 and 78643, which is 10000.
I'm not aware of any actual evidence having emerged that it is of any
value to set shared buffers higher than 10000.
--
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To: pgsql-performance@postgresql.org
Cc: cbbrowne@acm.org
Subject: Re: shared_buffer optimization
In-Reply-To: <87u04nv2q6.fsf@wolfe.cbbrowne.com>
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