linux shmmax

From: Graham Brereton <exit_music_ok@yahoo.co.uk>
Newsgroups: comp.os.linux.misc
Subject: Re: How to modify the value of SHMMAX?
Date: Sat, 16 Sep 2000 01:19:48 +0100
Message-ID: <39C2BCA4.BE9EB5AC@yahoo.co.uk> 
References: <8psmgs$2789$1@news.cz.js.cn> 

David wrote:
> 
> How to do it?
> Thanks

echo VAL > /proc/sys/kernel/shmmax (or something similar)


sysctl -w sys.kernel.shmmax=VAL (or something similar)

-- 
Don't get my sympathy hanging out the 15th floor...

And also you can set this with (for example)

echo "kernel.shmmax=2147483648" >> /etc/sysctl.conf
 

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3 comments

Wed Mar 30 12:04:08 2005: 248   anonymous


what is shared memory segment of a shmmax



Wed Mar 30 12:29:46 2005: 250   TonyLawrence


Not sure what you mean - SHMMAX sets the maximumum size of a shared memory segment - it's a kernel variable. Are you asking what it would like like in proc?
You can ses them in /proc/sysvipc/shm or use ipcs.. or do you mean where it would be in the map of a process? You can see that in /proc/(pid)/maps - and there's not a lot more I can tell you; I'm no kernel expert..

I can show you a shared segment as it looks on my system. Here's /proc/sysvipc/shm

 key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime
   0    1048576  1600     524288  7124  7124      1     0     0     0     0 1112173371          0 1112173371

and here's the line from /proc/7124/maps:

b6668000-b66e8000 rwxs 00000000 00:04 1048576    /SYSV00000000 (deleted)

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