Re: Solaris shared_buffers anomaly? - Mailing list pgsql-performance

From Tom Lane
Subject Re: Solaris shared_buffers anomaly?
Date
Msg-id 18773.1150250672@sss.pgh.pa.us
Whole thread Raw
In response to Re: Solaris shared_buffers anomaly?  (Mischa Sandberg <mischa@ca.sophos.com>)
Responses Re: Solaris shared_buffers anomaly?  (Mischa Sandberg <mischa@ca.sophos.com>)
List pgsql-performance
Mischa Sandberg <mischa@ca.sophos.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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