Messages in this thread | | | Date | Mon, 18 Jan 1999 20:08:59 +0100 (CET) | From | Rik van Riel <> | Subject | Re: [uPATCH] SMP scheduling fix (?) |
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On Fri, 15 Jan 1999, Pavel Machek wrote:
> > I'd _really_ like to have a nice value that says "don't run unless you > > are twiddling your thumbs". Ie a nice 20 perhaps, that says I don't > > want > > I'd like that, too. But it is currently impossible with linux: it > opens DoS attack. > > make your nice 20 task hold some lock, and then run 'normal' task so > that nice 20 task will never ever get cpu again. BOom, you are holding > lock and are not going to release it. > > Is there solution to this? Maybe processes running in kernel get > automagical priority boost?
An soon as a process gives up the CPU (and reschedules) it's in kernel mode. We can, however, use the arch-specific TSS structure to see if the task is in kernel mode.
Since we only have to do that when rescheduling SCHED_IDLE processes, the costs will actually be bearable for the kernel and Linus can be convinced that it's worth the trouble...
Rik -- If a Microsoft product fails, who do you sue? +-------------------------------------------------------------------+ | Linux memory management tour guide. riel@nl.linux.org | | Scouting Vries cubscout leader. http://www.nl.linux.org/~riel | +-------------------------------------------------------------------+
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