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Home > Archive > Red Hat Topics > August 2006 > Increasing number of semaphore sets(SEMMNI) in RHEL3.0
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Increasing number of semaphore sets(SEMMNI) in RHEL3.0
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| Pawan.Ghildiyal@gmail.com 2006-08-17, 7:15 am |
| Hi,
Does anybody knows that what is the maximum value of SEMMNI for redhat
enterprose linux
default is 128.
I want to increase this value to 512.
After increasing what this will effect to kernel or system resources.
and how to calculate that what is the most suitable value for SEMMNI
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| Jean-David Beyer 2006-08-17, 1:13 pm |
| Pawan.Ghildiyal@gmail.com wrote:
> Hi,
> Does anybody knows that what is the maximum value of SEMMNI for redhat
> enterprose linux
> default is 128.
> I want to increase this value to 512.
> After increasing what this will effect to kernel or system resources.
> and how to calculate that what is the most suitable value for SEMMNI
>
Here is part of my /etc/sysctl.conf file:
# Last item was 128: we raise to 1024.
# Guessing these items are, in order:
# max num of semaphores per id: 8000 MAX
# semaphore maximum value: 32767 MAX
# max num of ops per semop call: 1000 MAX
# max # of semaphore identifiers: IPCMNI MAX (32767)
kernel.sem=250 32000 32 1024
--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ PGP-Key: 9A2FC99A Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 11:55:01 up 3 days, 21:03, 4 users, load average: 4.20, 4.22, 4.10
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| Pawan.Ghildiyal@gmail.com 2006-08-18, 1:14 am |
|
Jean-David Beyer wrote:
> Pawan.Ghildiyal@gmail.com wrote:
> Here is part of my /etc/sysctl.conf file:
>
> # Last item was 128: we raise to 1024.
> # Guessing these items are, in order:
> # max num of semaphores per id: 8000 MAX
> # semaphore maximum value: 32767 MAX
> # max num of ops per semop call: 1000 MAX
> # max # of semaphore identifiers: IPCMNI MAX (32767)
> kernel.sem=250 32000 32 1024
>
> --
> .~. Jean-David Beyer Registered Linux User 85642.
> /V\ PGP-Key: 9A2FC99A Registered Machine 241939.
> /( )\ Shrewsbury, New Jersey http://counter.li.org
> ^^-^^ 11:55:01 up 3 days, 21:03, 4 users, load average: 4.20, 4.22, 4.10
Thanks Jean.
One more thing I want to know that what is the effect of increasing
semaphore set.
Do we need to increase memory.We are currently using 2GB of RAM
and Does it effect the system performance?
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| Jean-David Beyer 2006-08-18, 7:15 am |
| Pawan.Ghildiyal@gmail.com wrote:
> Jean-David Beyer wrote:
[vbcol=seagreen]
> Thanks Jean.
> One more thing I want to know that what is the effect of increasing
> semaphore set.
Probably uses a little more memory.
> Do we need to increase memory.
Probably not. If you are paging too much, then you need to increase memory.
> We are currently using 2GB of RAM
> and Does it effect the system performance?
>
It does (in theory anyway), but if you do not have enough semaphores, the
system (including your applications) will not operate at all.
--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ PGP-Key: 9A2FC99A Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 07:10:01 up 4 days, 16:18, 3 users, load average: 4.14, 4.13, 4.14
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| Scott Lurndal 2006-08-18, 7:12 pm |
| Pawan.Ghildiyal@gmail.com writes:
>
>One more thing I want to know that what is the effect of increasing
>semaphore set.
>Do we need to increase memory.We are currently using 2GB of RAM
>and Does it effect the system performance?
These defaults were established when 4MB was a _lot_ of memory.
Setting the SEMMNI value to 512 (or even 8192) will have negligable
affect on memory on a 2GB system.
scott
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