Messages in this thread | | | Date | Thu, 18 Feb 1999 23:53:50 +0100 | From | Pavel Machek <> | Subject | Re: Locking a process or thread onto a specific CPU |
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Hi!
> > Is there any way to do this with the 2.2 SMP code? A colleague is > > implementing his own language for research purposes and wants, in > > effect, to schedule his own threads on the available CPUs. The > > obvious way to do this seems to be to run one "real" thread locked > > onto each CPU. I know that threads will typically stay on the same > > CPU they were on anyway, but I can imagine an ill-timed intervention > > of a third process (in the case of 2 CPUs) resulting in both his > > processes trying to run on the same CPU. > > > > If this is not possible at the moment, can anyone (a) comment on its > > feasibility (b) advise us on where to look to implement it or (c) > > comment on its desirability as a new feature. > > I think this is very desirable. It is also desirable to be able to > disable some CPUs. I have one example where this kind of flexibility > is desirable.
I thought that there were patches to do this? It was pretty simple.
> We ran a 4-CPU SGI machine a while back. It was used by students and > obviously they did lots of weird things with it. Once in a while, a > student would write a program that essentially forked in a loop where > the parent process exited. This kind of process is _hard_ to kill > since neither is it visible using 'ps', nor is the PID constant. In > IRIX, it is easy to solve this problem by disabling 3 CPUs, and > scheduling your shell as a real-time process. Alternatively, you can > allocate one CPU to the OS, one for your shell, and disable the other > processes. None of this is possible in Linux. In Linux, on a 4-way > SMP system, you're stuck.
su (studentname) kill -9 -1
is the right way to do this kind of job. Well, all tasks of that student are going to die, but I think (s)he deserved it :-).
Pavel
-- I'm really pavel@atrey.karlin.mff.cuni.cz. Pavel Look at http://atrey.karlin.mff.cuni.cz/~pavel/ ;-).
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