System crashing when swap hits 25%

[Chris Snook]

Simon Slater wrote:
> On Mon, 2008-03-10 at 21:01 -0400, Chris Snook wrote:
>>>> 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.
>>
> 	Have just been through a few man pages.
> Temporarily, the command sysctl vm.overcommit_memory=2 would do the job?

By itself, probably not.

> What does the value '2' signify?

0 = heuristic overcommit
1 = always overcommit (until completely out of RAM + swap)
2 = overcommit (swap + (vm.overcommit_ratio * RAM))

> What do sysrq-m and sysrq-t do?  I haven't found them yet.

alt+sysrq+m prints memory statistics
alt+sysrq+t prints thread state information

> Oh, currently vm.overcommit_memory=0 and kernel.sysrq=0.

You'll need to set kernel.sysrq=1 for keyboard sysrq input to be 
honored.  If you set vm.overcommit_memory=2, then vm.overcommit_ratio 
will be honored.

-- Chris