Re: number of CPUs and IPI panic

On Thu, 2004-10-21 at 17:05, John Baldwin wrote:
> On Wednesday 20 October 2004 09:05 pm, Stephan Uphoff wrote:
> > Can you try the attached patch?
> > ( Hope it still applies since it is a few weeks old)
> >
> > If this does not work I have a few more questions next week.
> 
> Unfortunately it can enable interrupts with sched_lock held which can result 
> in deadlocks due to ithread preemption (IIRC, maybe not as badly with the 
> newer preemption code.)

The code only enables interrupts for TLB shootdowns.
In this case it is guaranteed that it holds the smp_ipi_mtx that as a
side effect protects it against preemption and holds no other spin
mutex.
I don't see the problem.

I am thinking about implementing the bitmap based stuff be talked about
a few weeks ago to avoid having more than one queued IPI of the same
type.

> 
> > 	Stephan
> >
> > On Wed, 2004-10-20 at 18:16, Nik Azim Azam wrote:
> > > sorry for not posting this information earlier.
> > >
> > > i'm running on SCHED_4BSD, with PREEMPTION. the same
> > > panic occours without PREEMPTION. the kernel is
> > > generic except that i've removed some devices that i
> > > dont need.
> > >
> > > --- Gavin Atkinson <gavin.atkinson_at_ury.york.ac.uk>
> > >
> > > wrote:
> > > > On Wed, 20 Oct 2004, Nik Azim Azam wrote:
> > > > > hello list,
> > > > >
> > > > > i'm doing some testing on a 6 cpu pentium II
> > > >
> > > > overdrive
> > > >
> > > > > computer with 6-CURRENT. with 6 cpus, the system
> > > >
> > > > will
> > > >
> > > > > panic easily with moderate load (previous IPI is
> > > > > stuck). i edited sys/i386/sys/param.h file and
> > > >
> > > > lowered
> > > >
> > > > > the MAXCPU to 4. now the system is running with 4
> > > >
> > > > cpus
> > > >
> > > > > and it survived a make buildworld + portupgrade at
> > > >
> > > > the
> > > >
> > > > > same time.
> > > > >
> > > > > is this a known problem? i can give more
> > > >
> > > > information
> > > >
> > > > > if anyone interested.
> > > >
> > > > Are you using SCHED_ULE? (I believe it's the default
> > > > in 6-CURRENT...)
> > > >
> > > > If so, try with SCHED_4BSD. ULE has known problems
> > > > at the moment.
> > > >
> > > > Gavin
> > >
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