Using adb to change hidden kernel params

[Chris Garman]

Hi,

My Oracle users are getting errors that the process is out of memory. The o/s does not log this problem. I have tracked down a kernel parameter called mman_elog that I need to enable to activate such logging. Can anyone help with information re how to activate this param?

Thanks,
Chris

[Stefan Farrelly]

echo "mman_elog?W 1" | adb -w /stand/vmunix

You should see a message back like;

mman_elog: 0 = 1

Then reboot.

[Andy Monks]

Turning this on isn't actually going to help much. Your just going to get a message on the console/dmesg saying what pid failed to grow it's stack or data area.

You'd be better off checking things like the maxdsiz/maxssiz and the swap space usage (with swapinfo -tm) and then check the bottom line only.

[Alan Riggs · Accepted solution]

Check the attached document for some good information on how to get a view into shared memory using adb.

[Chris Garman]

Thanks for the replies.

Steve,

Ithere a way to change the param on the fly? This is in case a reboot clears the problem.

Andy,

Those params were already at about 128Mb, the actual cause was some dodgy data in the tables.

Alan,

Thanks for the doc. Do you know how process memory relates to shared memory? I wish the response centre had told me about the ipcs command when I spoke to them!

[Stefan Farrelly]

Chris,

nope, no way to modify it on the fly. All you can do is 'patch' the kernel (cant even set it in the system file!) and if you ever rebuild the kernel or say install a patch which rebuilds it you will need to make the adb change again! mman_elog is not a tunable parameter.

[Chris Garman]

Thanks Stefan,

At this rate you should be royalty by tomorrow!!
Do you work for HP?

chris

[Stefan Farrelly]

Hi Chris,

sort of. Im a self employed contractor, have been for a long time. Im currently on contract to HP in London. Dont tell my boss, I must have too much free time to be answering all these questions!