Re: [PATCH] Softlockup (out of cpu) killer

[Peter Zijlstra]

On Sun, 2011-12-11 at 14:48 -0800, Vincent Li wrote:
> In kernel, there is out of memory (OOM) killer, why not make an out of cpu (OOC) killer?
> I tested following patch by running an user-space cpu hogging process and the softlockukp
> detector killed the process successfully.
> 
>  Softlockup could be caused by user-space process hogging cpu, add softlockup_kill kernel
>  config to allow kernel to kill the user space cpu hogging process. this feature is
>  useful for high availability systems that have uptime gurantees and where a softlockup
>  must be resolved ASAP
> 
> echo 1 > /proc/sys/kernel/softlockukp_kill to enable cpu hog process killer
> echo 0 > /proc/sys/kernel/softlockup_kill to disable cpu hog process killer
> 
> Signed-off-by: Vincent Li <vincent.mc.li@xxxxxxxxx>

Your whole premise is broken. Being a cpu hog and the softlockup
mechanism aren't related at all.

Furthermore, since the normal scheduling policy is a proportional one, a
cpu hog can't in fact starve anybody (although a fork bomb could). And
FIFO/RR are privileged ops.

Furthermore the distinction between memory and cpu-time is that memory
isn't a renewable resource, whereas time is. There's always more time,
but there's not always more memory.

So no, I don't think either you patch nor your concept make any sense.
Consider it nacked. 
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