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Re: Setting shared buffers

From: Carlos Moreno <moreno(at)mochima(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Setting shared buffers
Date: 2002-10-28 22:07:42
Message-ID: 3DBDB52E.500@mochima.com (view raw or flat)
Thread:
Lists: pgsql-performance
Thanks John!  This is very helpful...

Just one detail I'd like to double check:
 

>It's easy, on Linux  don't even have to reboot.  Other OS's are harder.
> See this very helpful page:
>http://www.us.postgresql.org/users-lounge/docs/7.2/postgres/kernel-resources.html#SYSVIPC
>
>In fact, I tend to up my SHMMAX and SHMMALL and shared_buffers [...]
>

According to that document, I should put the same value for the
SHMMAX and SHMMALL -- however, when I do:

  cat /proc/sys/kernel/shmmax
  cat /proc/sys/kernel/shmmall

on my Linux system (RedHat 7.3, soon to upgrade to 8.0), I
get different values, shmmall being shmmax divided by 16

Is that normal?  What should I do?  Should I follow the exact
same instructions from that document and set both to the
exact same value?

Are the default values set that way (i.e., different values)
for some strange reason, or is it that on the 2.4 kernel
the shmmall is indicated in blocks of 16 bytes or something
like that?

Thanks!

Carlos
--



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