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Operating System - Tru64 Unix
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Limiting physical memory

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Rene Poisson
Occasional Visitor

Limiting physical memory

Running Tru64 5.1a on an ES40 2 CPUs 2GB

I wish to watch performance hit of some processes on that machine but I have also some target systems having less memory and only one CPU.

So... I want to simulate those last platforms using my actual system.
I found out how to stop one CPU using sysman but I can't figure out how to limit the physical memory (without opening the box).
Beeing a former DECie used to OpenVMS where I had just to change the system parameter PHYSICAL_MEMORY to whatever I wanted, I wonder if there is a similar way of doing the magic under Tru64.

Thanks
2 REPLIES
VINCENT, Jean-Marc
Valued Contributor
Solution

Re: Limiting physical memory

Dear René,

You can limit the amount of available memory to your Tru64 only at boot time by specifying the amount of memory in megabytes you want to use. So you will have to reboot your system:

In V4 (128MBytes as example):
>>> boot -fl i
(boot dqa1.1.0.13.0 -flags i)
block 0 of dqa1.1.0.13.0 is a valid boot block
reading 16 blocks from dqa1.1.0.13.0
bootstrap code read in
base = 200000, image_start = 0, image_bytes = 2000
initializing HWRPB at 2000
initializing page table at 3ff2e000
initializing machine state
setting affinity to the primary CPU
jumping to bootstrap code

Digital UNIX boot - Thu Jan 11 14:49:49 EST 2001


Enter [option_1 ... option_n]
Hit to boot default kernel 'vmunix': vmunix memlimit=128
Loading vmunix ...
Loading at 0xfffffc0000230000
Current PAL Revision <0x1004f0001015d>
Switching to OSF PALcode Succeeded
New PAL Revision <0x1004600020158>

Sizes:
text = 4744912
data = 855760
bss = 1308272
Starting at 0xfffffc0000576030

Loading vmunix symbol table ... [1301960 bytes]
Kernel argument memlimit = 0x80
Alpha boot: available memory from 0xc50000 to 0x7f2c000
Digital UNIX V4.0F (Rev. 1229); Fri Feb 11 16:16:46 MET 2005
physical memory = 128.00 megabytes.
available memory = 114.87 megabytes.
using 480 buffers containing 3.75 megabytes of memory
Firmware revision: 6.1-2
PALcode: Digital UNIX version 1.88-70
COMPAQ AlphaServer DS10 617 MHz
.....

In V5 (128Mbytes as example):
>>> boot -fl i
(boot dkc0.0.0.15.0 -flags i)
block 0 of dkc0.0.0.15.0 is a valid boot block
reading 19 blocks from dkc0.0.0.15.0
bootstrap code read in
base = 200000, image_start = 0, image_bytes = 2600(9728)
initializing HWRPB at 2000
initializing page table at 1ff2c000
initializing machine state
setting affinity to the primary CPU
jumping to bootstrap code

UNIX boot - Wednesday August 09, 2006


Enter: [option_1 ... option_n]
or: ls [name]['help'] or: 'quit' to return to console
Press Return to boot 'vmunix'
# vmunix generic:memlimit=128
Loading vmunix ...
Loading at 0xfffffc0000230000

Sizes:
text = 7121088
data = 1406448
bss = 1929696
Starting at 0xfffffc0000242f30

Loading vmunix symbol table ... [1722912 bytes]
Kernel argument generic:memlimit=128
Memory trolling not supported, cpu Major id 11, Minor id 14
Alpha boot: available memory from 0x126c000 to 0x7f2a000
Compaq Tru64 UNIX V5.1B (Rev. 2650); Wed Aug 23 18:16:09 MEST 2006
physical memory = 128.00 megabytes.
available memory = 108.73 megabytes.
using 434 buffers containing 3.39 megabytes of memory
Firmware revision: 7.2-1
PALcode: UNIX version 1.92-73
AlphaServer DS10 617 MHz
.....

Hope this will help you.

Kind Regards,

VINCENT Jean-Marc
HP France
Groupe Support Unix
Tru64(tm) UNIX Technical Consultant - Tru64(tm) UNIX Ambassador HP France
+33 1 5762-8861
jean-marc.vincent@hp.com
Rene Poisson
Occasional Visitor

Re: Limiting physical memory

Thanks for your timely response.

I am happy with your explanations as I figured out I had to reboot anyway (even OpenVMS had to be rebooted after limiting the memory)

Rene Poisson

PS: Merci Jean-Marc c'est sympa d'avoir des news des anciens...