Re: [sched] fix sched_domains hotplug bootstrap ordering vs. cpu_online_mapissue

[Nick Piggin]

William Lee Irwin III wrote:
> William Lee Irwin III <wli@xxxxxxxxxxxxxx> wrote:
>
> > > This is the whole thing; the "other half" referred to a new hunk added to
> > > the patch (identical to this one) posted in its entirety.
>
>
> On Fri, Sep 03, 2004 at 03:34:34PM -0700, Andrew Morton wrote:
>
> > ho-hum. changelog, please?
>
>
> cpu_online_map is not set up at the time of sched domain initialization
> when hotplug cpu paths are used for SMP booting. At this phase of
> bootstrapping, cpu_possible_map can be used by the various
> architectures using cpu hotplugging for SMP bootstrap, but the
> manipulations of cpu_online_map done on behalf of NUMA architectures,
> done indirectly via node_to_cpumask(), can't, because cpu_online_map
> starts depopulated and hasn't yet been populated. On true NUMA
> architectures this is a distinct cpumask_t from cpu_online_map and so
> the unpatched code works on NUMA; on non-NUMA architectures the
> definition of node_to_cpumask() this way breaks and would require an
> invasive sweeping of users of node_to_cpumask() to change it to e.g.
> cpu_possible_map, as cpu_possible_map is not suitable for use at
> runtime as a substitute for cpu_online_map.
>
> Signed-off-by: William Irwin <wli@xxxxxxxxxxxxxx>

Yeah I guess this is probably the best thing to do for now.

Martin, I wonder if this patch fixes your z/VM problem?
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/