topic shmmax increase in Operating System - HP-UX

shmmax increase

Javier Ortiz Guajardo — Wed, 12 Jan 2005 10:46:56 GMT

we increase the physical memory from 3.5 Gb to 8Gb. we have a hpux 11.0 64 bits.
The shmmax value is 1073741824.

how can i tune this parameter?

Re: shmmax increase

Jan Sladky — Wed, 12 Jan 2005 10:54:07 GMT

Hi Javier,

try kmtune command.

rgds Jan

Re: shmmax increase

Geoff Wild — Wed, 12 Jan 2005 10:57:11 GMT

By either the command line or use sam.

http://docs.hp.com/en/5990-8172/ch03s09.html#cjacdbcg

Rgds...Geoff

Re: shmmax increase

Steven E. Protter — Wed, 12 Jan 2005 10:57:43 GMT

shmmax will only go up to 25% of total memory.

Memory is defined as swap plus ram. If you exceed that figure it will be ignored by the system.

SEP

Re: shmmax increase

Hoang Chi Cong_1 — Wed, 12 Jan 2005 11:01:58 GMT

Hi

Please refer to this thread:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=773637

Anyway, when tune this parameter, it depend on the application is running on your system...
To tune it just do:
+kmtune -s shmmax=
+/usr/lbin/sysadmin/system_prep -s system
+mk_kernel -s system
+kmpudate

And then copy /stand/vmunux to vumunix.bak

Then copy the new one to vmunux

shutdown -ry

Hope this helps
HoangChiCong

Re: shmmax increase

Hoang Chi Cong_1 — Wed, 12 Jan 2005 11:05:13 GMT

And here is good for you about shmmax kernel parameter:
http://docs.hp.com/en/B2355-60105/shmmax.5.html

Regard,
HoangChiCong

Re: shmmax increase

MAUCCI_2 — Thu, 13 Jan 2005 13:52:24 GMT

Steven,

are you sure of what you said?
AFAIK, shmmax is just a barrier to prevent somebody from eating up all memory.
It can be set far above total memory on the system.

++Cyrille

# kmtune -u -s shmmax=0xFFFFFFFFF
The kernel's value of shmmax has been set to 68719476735 (0xfffffffff).
# swapinfo -mt
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 4096 0 4096 0% 0 - 1 /dev/vg00/lvol2
reserve - 4096 -4096
memory 6666 5812 854 87%
total 10762 9908 854 92% - 0 -
# kmtune | grep shmmax
shmmax 0xfffffffff Y 0xFFFFFFFFF