Subject: Re: CCL:G:g94: shmget failed on SGI O2000

From: Sigismondo Boschi <[email-masked]>
Date: Thu, 3 Dec 1998 12:16:22 +0100 (MET)

Hi Guido,

do you remember me?

I have compiled g94 (e2) on an SGI origin2000 (IRIX 6.4) and I can report 
my personal experience with it.

g94 uses "system V shared memory" (shmget) for allocating the main pool 
memory on the origin, in order all the processors can use it.

In the beginning I found that the jobs I could run was very small 
with respect the memory Origin installed here at CINECA: 16CPUs with a 
total of 8GB.

After all I have found that the "maximum segment" allocable is a 
parameter of the kernel, set to 512MB by default (if I 
remember right). Its maximum value is instead 1/4 of the toatal memory, 
2GB for our machine (256MWords).

After the system manager have changed this parameter, I was able to run 
problems up to 250MWords of in-core memory.

The name of the adjusted kernel parameter is "shmmax" and it is one of the 
"IPC parameters".

If you have the same problem, I think you need to change it and recompile 
the kernel. 

I hope it helps. Bye!

   Sigismondo

 --------------------------------------- ---------------------------------
|Sigismondo Boschi                      |tel: +39 51 6171559              |
|CINECA (Gruppo Supercalcolo) - INSTM	|fax: +39 51 6132198              |
|via Magnanelli, 6/3                    |e-mail: [email-masked]       |
|40033 Casalecchio di Reno (Bologna)    |                                 |
|ITALY                                  |                                 |
 --------------------------------------- ---------------------------------

On Wed, 2 Dec 1998, Guido Germano wrote:

> Two days ago I compiled g94 D4 on a SGI Origin 2000 running IRIX 6.5.1.
> The same geometry optimizations that run fine on an IBM core dump after
> two steps in l301 with "shmget failed" as the last line of the output
> file. If restarted from the chk, they do other two steps, then core dump
> again, and so on. I have "unlimit" in my .login before I source
> g94.login. Increasing %mem is no help (the default of 4000000 words is
> enough anyway). The Origin has 8 processors with 1 GB of RAM.
> 
> I searched the CCL archives and found the same question being asked
> about g92, but no answer. So far no answer from help@gaussian either.
> 
> Guido Germano
> 
> University of Bristol, +44-117-928 9000 ext. 8755
> http://www.phy.bris.ac.uk/staff/germano_g.html
> 
> 
> 
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