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SubjectRe: [RFC][PATCH 0/2] Quicklist is slighly problematic.
On Thu, Aug 21, 2008 at 08:07:43AM -0500, Christoph Lameter wrote:
> Robin Holt wrote:
> >
> > Index: ia64-cleanups/include/linux/quicklist.h
> > ===================================================================
> > --- ia64-cleanups.orig/include/linux/quicklist.h 2008-08-20 21:35:10.000000000 -0500
> > +++ ia64-cleanups/include/linux/quicklist.h 2008-08-20 21:38:00.891943270 -0500
> > @@ -66,6 +66,15 @@ static inline void __quicklist_free(int
> >
> > static inline void quicklist_free(int nr, void (*dtor)(void *), void *pp)
> > {
> > +#ifdef CONFIG_NUMA
> > + unsigned long nid = page_to_nid(virt_to_page(pp));
> > +
> > + if (unlikely(nid != numa_node_id())) {
> > + free_page((unsigned long)pp);
> > + return;
> > + }
> > +#endif
> > +
> > __quicklist_free(nr, dtor, pp, virt_to_page(pp));
> > }
> >
>
> We removed this code because it frees a page before the TLB flush has been
> performed. This code segment was the reason that quicklists were not accepted
> for x86.

How could we do this. It was a _HUGE_ problem on altix boxes. When you
started a jobs with a large number of MPI ranks, they would all start
from the shepherd process on a single node and the children would
migrate to a different cpu. Unless subsequent jobs used enough memory
to flush those remote quicklists, we would end up with a depleted node
that never reclaimed.

Thanks,
Robin


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