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From: "Qingqing Zhou" <zhouqq@cs.toronto.edu>
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Subject: Re: 8.1beta, SunOS and shmget
Date: Mon, 29 Aug 2005 09:37:27 -0400
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""Sergey E. Koposov"" <math@sai.msu.ru> wrote
>
> selecting default max_connections ... 10
> selecting default shared_buffers ... 50
> DETAIL:  Failed system call was shmget(key=1, size=1957888, 03600).
>
> selecting default max_connections ... 10
> selecting default shared_buffers ... 20
> DETAIL:  Failed system call was shmget(key=1, size=1712128, 03600).
>
> selecting default max_connections ... 5
> selecting default shared_buffers ... 16
> DETAIL:  Failed system call was shmget(key=1, size=1613824, 03600).
>
> To me it seems quite strange, since that behaviour does not relate with
> the formulae "250 kB + 8.2 kB * shared_buffers + 14.2 kB * max_connections
> up to infinity" from documentation.
>

If the linear relationship is still held, the shm formula induced from your 
test is:

    1384 kB + 8 kB * shared_buffers + 12.8 kB * max_connections

Seems in 8.1, the base shm requirement is increased. But I am not where they 
are from.

Regards,
Qingqing