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Måns Rullgård wrote: >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. > > > Please google "emoticons" and find out what those funny characters at the end of the of the paragraph you quoted really mean. Sheesh! -- bill davidsen <davidsen@tmr.com> CTO TMR Associates, Inc Doing interesting things with small computers since 1979 - 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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