Re: postgresql-8.0.1 performance tuning - Mailing list pgsql-performance

From Mark Kirkwood
Subject Re: postgresql-8.0.1 performance tuning
Date
Msg-id 429D56B2.9070302@paradise.net.nz
Whole thread Raw
In response to Re: postgresql-8.0.1 performance tuning  (Cosimo Streppone <cosimo@streppone.it>)
Responses Re: postgresql-8.0.1 performance tuning
SHMMAX / SHMALL Was (Re: postgresql-8.0.1 performance tuning)
List pgsql-performance
Cosimo Streppone wrote:
> ######### Config ############
>> /etc/sysctl.conf:
>> kernel.shmall = 786432000
>> kernel.shmmax = 786432000
>
>
> I think you have a problem here.
> kernel.shmmax should *not* be set to an amount of RAM, but
> to maximum number of shared memory pages, which on a typical linux system
> is 4kb. Google around:
>
>
>

This is somewhat confusing :

kernel.shmmax is in bytes (max single segment size)
kernel.shmall is in (4k) pages (max system wide allocated segment pages)

cheers

Mark



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