Messages in this thread | | | Date | Sat, 08 Apr 2006 11:29:16 +1000 | From | Peter Williams <> | Subject | Re: [ANNOUNCE][RFC] PlugSched-6.3.1 for 2.6.16-rc5 |
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Al Boldi wrote: > Peter Williams wrote: >> Al Boldi wrote: >>> Peter Williams wrote: >>>> Al Boldi wrote: >>>>> Peter Williams wrote: >>>>>> Al Boldi wrote: >>>>>>>>>> Control parameters for the scheduler can be read/set via files >>>>>>>>>> in: >>>>>>>>>> >>>>>>>>>> /sys/cpusched/<scheduler>/ >>>>>>> The default values for spa make it really easy to lock up the >>>>>>> system. >>>>>> Which one of the SPA schedulers and under what conditions? I've been >>>>>> mucking around with these and may have broken something. If so I'd >>>>>> like to fix it. >>>>> spa_no_frills, with a malloc-hog less than timeslice. Setting >>>>> promotion_floor to max unlocks the console. >>>> OK, you could also try increasing the promotion interval. >>> Seems that this will only delay the lock in spa_svr but not inhibit it. >> OK. But turning the promotion mechanism off completely (which is what >> setting the floor to the maximum) runs the risk of a runaway high >> priority task locking the whole system up. IMHO the only SPA scheduler >> where it's safe for the promotion floor to be greater than MAX_RT_PRIO >> is spa_ebs. So a better solution is highly desirable. > > Yes. > >> I'd like to fix this problem but don't fully understand what it is. >> What do you mean by a malloc-hog? Would it possible for you to give me >> an example of how to reproduce the problem? > > Can you try the attached mem-eater passing it the number of kb to be eaten. > > i.e. '# while :; do ./eatm 9999 ; done' > > This will print the number of bytes eaten and the timing in ms. > > Adjust the number of kb to be eaten such that the timing will be less than > timeslice (120ms by default for spa). Switch to another vt and start > pressing enter. A console lockup should follow within seconds for all spas > except ebs.
This doesn't seem to present a problem (other than the eatme loop being hard to kill with control-C) on my system using spa_ws with standard settings. I tried both UP and SMP. I may be doing something wrong or perhaps don't understand what you mean by a console lock up. When you say "less than the timeslice" how much smaller do you mean?
Peter PS I even managed to do a kernel build with the eatme loop running on a single processor system. -- Peter Williams pwil3058@bigpond.net.au
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