On Wed, 5 Aug 2015 13:51:21 -0700 Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > 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... No problem, in the meantime I found another solution for my problem. But thanks for trying :-) Michael -- 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
