System crashing when swap hits 25%

Chris Snook csnook at redhat.com
Tue Mar 11 01:01:36 UTC 2008


Simon Slater wrote:
> On Mon, 2008-03-10 at 18:51 -0400, Chris Snook wrote:
>> I suggest setting vm.overcommit_memory=2 with sysctl to turn on
>> explicit 
>> overcommit control, and then try changing the value of 
>> vm.overcommit_ratio to see if that changes where your system dies.
>>
> I've never come across these variables/commands before, so I'll go
> slowly here. 
> 
>> Also, is the system actually crashing, or does it just get swaplocked 
>> and hang indefinitely when swap usage reaches 25%?  See if you can
>> get 
>> sysrq-m and sysrq-t data out of the system.  You'll want to set 
>> kernel.sysrq=1 first. 
> Where do I find these?
> 

There are two interfaces.  One is the /proc/sys directory, and the other 
is sysctl.  If you want to set something with sysctl, the easy way is to 
add a line in sysctl.conf (for example: vm.overcommit_memory=2) and then 
run sysctl -p to process the config file again.

-- Chris




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