On Thu, Jul 30, 2015 at 08:35:51PM +0200, Michael Holzheu wrote: > Hello Greg, > > Is it possible to use "from_nid = cpu->node_id"? > > Background: > > I am currently working on (fake) NUMA support for s390. At startup, for > "deconfigured" CPUs, we don't know to which nodes the CPUs belong. Therefore > we always return node 0 for cpu_to_node(). > > For each present CPU the register_cpu() function is called which sets an > initial NUMA node via cpu_to_node(), which is then first node 0 for > "deconfigured" CPUs on s390. > > After we "configure" a CPU we know to which node it belongs. Then when setting > a CPU online, the following is done in cpu_subsys_online(): > > from_nid = cpu_to_node(cpuid); -> we return node x > cpu_up(cpuid); > to_nid = cpu_to_node(cpuid); -> we return node x > if (from_nid != to_nid) -> x != x -> false > change_cpu_under_node(cpu, from_nid, to_nid); > > The result is that each CPU that was deconfigured at boot time stays in > node 0 because cpu_to_node() returns the same node before and after > setting the CPU online. > > Using "cpu->node_id" for "from_nid" instead of calling cpu_to_node() > would help in our case. > > Signed-off-by: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx> > --- > drivers/base/cpu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index f160ea4..2dd889c 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -47,7 +47,7 @@ static int __ref cpu_subsys_online(struct device *dev) > int from_nid, to_nid; > int ret; > > - from_nid = cpu_to_node(cpuid); > + from_nid = cpu->node_id; > if (from_nid == NUMA_NO_NODE) > return -ENODEV; > I really have no idea the answer to any of these questions, sorry... -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
