topic maxdsiz in Operating System - HP-UX

maxdsiz

Madhu Sudhan_1 — Wed, 06 Feb 2002 18:53:06 GMT

Friends,

What is the maxdsiz equivalent parameter in Solaris ? Please excuse if I have posted it wrong place. Curious to know.

Thank you.

Re: maxdsiz

harry d brown jr — Wed, 06 Feb 2002 21:43:23 GMT

Allen,

I'm not sure there is a DOCUMENTED direct relationship, but:

There is often a need to change the default har d and soft limit values. Sometimes the maximums need to be r educed to keep processes from hogging the system and sometimes the default number of files needs to be incr eased. Rather than setting limits in every user login script the global default limits in the kernel can be changed. In generic Unix System V Release 4 this is performed by setting some symbolic variables and r ebuilding the kernel. In Solaris 2 the /etc/system method cannot be used since there are no variables corresponding to the individual limits, just a single rlimits data str ucture. The kernel must be patched using adb. The elements ar e laid out as shown by the sysdef -i command, which shows the values in hexadecimal.

To increase the default number of file descriptors per pr ocess rlimits+28 must be patched with adb as shown below .

The commands shown below permanently patch the default number of file descriptors to 128 (0x80) in the /kernel/unix file using "?" and also patch the current copy in memory using "/".

Soft:Hard Resource byte offset in hex Infinity:Infinity cpu time 0: 4 Infinity:Infinity file size 8: c 1fefe000:1fefe000 heap size 10:14 800000: ff00000 stack size 18:1c Infinity:Infinity core file size 20:24 40: 400 file descriptors 28:2c Infinity:Infinity mapped memory 30:34

# cp /kernel/unix /kernel/unix.orig # adb -k -w /kernel/unix /dev/mem rlimits,e?X rlimits: rlimits: 7fffffff 7fffffff 7fffffff 7fffffff 1fefe000 1fefe000 800000 ff00000 7fffffff 7fffffff 40 400 7fffffff 7fffffff

Warning - using adb to patch the kernel dir ectly is a potentially danger ous operation. Mistyping a command could crash the system or r ender it unbootable. Save an unpatched kernel copy . Do not incr ease the hard limits.

Buffer Sizes And Tuning Variables 49

from:
http://www.cs.ualberta.ca/operations/Doc/Sun-Tuning/SunPerfOvDec93.ps.gz

in Solaris, it's the HEAP (datasize in ulimit). Using the mapping above you can change it - good luck!!!

live free or die
harry

Re: maxdsiz

Steven Sim Kok Leong — Thu, 07 Feb 2002 03:09:26 GMT

Hi,

I agree with Harry.

In Solaris, using ulimit with the -d option sets the maximum size of a process's data segment eg.

# ulimit -d 65536

This sets the process's maximum data segment size to 64 MB.

Hope this helps. Regards.

Steven Sim Kok Leong

Re: maxdsiz

Madhu Sudhan_1 — Thu, 07 Feb 2002 11:30:32 GMT

Great response Harry ! Thanks a lot.
Allen.

Re: maxdsiz

harry d brown jr — Thu, 07 Feb 2002 12:01:28 GMT

Allen,

I spent at least three hours on that one. I have a sparky-ultra5 on my desk (that I use about twice a month), and I even asked my consultant and they had no clue. But it was time well spent, because I believe that Hp approached the issue correctly by making this a true kernel parameter. I don't want some rogue runaway program consuming memory like candy. If I have a need, and I have, I jack maxdsiz up, but only based upon need not greed :-))

live free or die
harry