On Tue, Mar 21, 2000 at 06:09:25AM +0100, Andi Kleen wrote:
> lk@tantalophile.demon.co.uk (Jamie Lokier) writes:
>
> > Jun Sun wrote:
> > > First of all, I think this is must-fix bug. (Any arguments here?)
> >
> > There are a few other scenarious where need_resched is missed, including
> > the last few instructions after ret_from_syscall. And it really does
> > happen there. I think it's a must-fix too, but the fact that neither my
> > nor Ingo's patch made it in suggests Linus thinks otherwise.
>
> Looks like the easiest way to fix such races would be to move need_resched
> back to a global variable (possible in an array indexed per CPU). Earlier
> Linux kernels (<2.0) had it this way, I'm not sure why it was changed.
Better would be to turn it into a per-architecture function. On PA-RISC,
we can set a bit in the CPU to make it trap on transitions to userspace
and having a set_resched() function which just sets the need_resched
flag on x86 but sets the L bit on PA-RISC would mean that we could avoid
checking the flag. Maybe this is a 2.5 thing though.
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This archive was generated by hypermail 2b29 : Thu Mar 23 2000 - 21:00:33 EST