Re: Solaris shared_buffers anomaly?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: mischa(at)ca(dot)sophos(dot)com
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Solaris shared_buffers anomaly?
Date: 2006-06-14 02:04:32
Message-ID: 18773.1150250672@sss.pgh.pa.us
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Mischa Sandberg <mischa(at)ca(dot)sophos(dot)com> writes:
> Tom Lane wrote:
>> Does Solaris have any call that allows locking a shmem segment in RAM?

> Yes, mlock(). But want to understand what's going on before patching.

Sure, but testing it with mlock() might help you understand what's going
on, by eliminating one variable: we don't really know if the shmem is
getting swapped, or something else.

> For a dedicated DB server machine, Solaris has a feature:
> create "intimate" shared memory with shmat(..., SHM_SHARE_MMU).
> All backends share the same TLB entries (!).

We use that already. (Hmm, might be interesting for you to turn it
*off* and see if anything changes. See src/backend/port/sysv_shmem.c.)

regards, tom lane

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