Re: can I bring Linux down by running "renice -20 cpu_intensive_process"?

[Bill Davidsen]

Måns Rullgård wrote:
> Lee Revell <rlrevell@xxxxxxxxxxx> writes:
>
> > On Fri, 2006-03-10 at 22:01 +0000, Måns Rullgård wrote:
> > > Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx> writes:
> > >
> > > > > Subject: can I bring Linux down by running "renice -20
> > > > > cpu_intensive_process"?
> > > > Depends on what the cpu_intensive_process does. If it tries to
> > > > allocate lots of memory, maybe. If it's _just_ CPU (as in `perl
> > > > -e '1 while 1'`), you get a chance that you can input some
> > > > commands on a terminal to kill it.  SCHED_FIFO'ing or
> > > > SCHED_RR'ing such a process is sudden death of course.
> > > Sysrq+n changes all realtime tasks to normal priority.
> > A nice -20 SCHED_OTHER task is not realtime, only SCHED_FIFO and
> > SCHED_RR.
>
> Maybe extending sysrq+n to lower the priority of -20 tasks would be a
> good idea.
If it runs before the keyboard thread it doesn't matter... But why 
should this hang anything, when there should be enough i/o to get out of 
the user process. There's a good fix for this, don't give this guy root 
any more ;-)

--
   -bill davidsen (davidsen@xxxxxxx)
"The secret to procrastination is to put things off until the
 last possible moment - but no longer"  -me

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