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Bill Davidsen <davidsen@tmr.com> writes: > Måns Rullgård wrote: >> Lee Revell <rlrevell@joe-job.com> writes: >> >>> On Fri, 2006-03-10 at 22:01 +0000, Måns Rullgård wrote: >>>> Jan Engelhardt <jengelh@linux01.gwdg.de> 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... Of course not, but that's not generally the case. > 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 ;-) Ever heard of bugs? Anyone developing a program can make a mistake. If the program runs with realtime scheduling a bug that makes it enter an infinite loop (or do something else that hogs the CPU) can be difficult to find since it rather efficiently locks you out. -- Måns Rullgård mru@inprovide.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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