Re: [PATCH v2 2/3] powerpc/numa: Prefer node id queried from vphn

[Srikar Dronamraju]

* Gautham R Shenoy  [2020-04-29 12:22:29]:

> Hello Srikar,
> 
> 
> > +   if (nid == NUMA_NO_NODE) {
> > +   cpu = of_get_cpu_node(i, NULL);
> > +   if (cpu) {
> 
> Why are we not retaining the BUG_ON(!cpu) assert here ?
> 
> > +   nid = of_node_to_nid_single(cpu);
> > +   of_node_put(cpu);
> > +   }
> > +   }
> 
> Is it possible at this point that both vphn_get_nid(i) and
> of_node_to_nid_single(cpu) returns NUMA_NO_NODE ? If so,
> should we still call node_set_online() below ?

Yeah, I think It makes sense to retain the BUG_ON and if check.

Will incorporate both of them in the next version.

> 
> 
> > node_set_online(nid);
> > }
> > 
> > -- 
> > 2.20.1
> > 
> --
> Thanks and Regards
> gautham.

-- 
Thanks and Regards
Srikar Dronamraju

Re: [PATCH v2 2/3] powerpc/numa: Prefer node id queried from vphn

[Gautham R Shenoy]

Hello Srikar,

On Tue, Apr 28, 2020 at 03:08:35PM +0530, Srikar Dronamraju wrote:
> Node id queried from the static device tree may not
> be correct. For example: it may always show 0 on a shared processor.
> Hence prefer the node id queried from vphn and fallback on the device tree
> based node id if vphn query fails.
> 
> Cc: linuxppc-...@lists.ozlabs.org
> Cc: linux...@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Cc: Michal Hocko 
> Cc: Mel Gorman 
> Cc: Vlastimil Babka 
> Cc: "Kirill A. Shutemov" 
> Cc: Christopher Lameter 
> Cc: Michael Ellerman 
> Cc: Andrew Morton 
> Cc: Linus Torvalds 
> Signed-off-by: Srikar Dronamraju 
> ---
> Changelog v1:->v2:
> - Rebased to v5.7-rc3
> 
>  arch/powerpc/mm/numa.c | 16 
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index b3615b7fdbdf..281531340230 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -719,20 +719,20 @@ static int __init parse_numa_properties(void)
>*/
>   for_each_present_cpu(i) {
>   struct device_node *cpu;
> - int nid;
> -
> - cpu = of_get_cpu_node(i, NULL);
> - BUG_ON(!cpu);
> - nid = of_node_to_nid_single(cpu);
> - of_node_put(cpu);
> + int nid = vphn_get_nid(i);
> 
>   /*
>* Don't fall back to default_nid yet -- we will plug
>* cpus into nodes once the memory scan has discovered
>* the topology.
>*/
> - if (nid < 0)
> - continue;


> + if (nid == NUMA_NO_NODE) {
> + cpu = of_get_cpu_node(i, NULL);
> + if (cpu) {

Why are we not retaining the BUG_ON(!cpu) assert here ?

> + nid = of_node_to_nid_single(cpu);
> + of_node_put(cpu);
> + }
> + }

Is it possible at this point that both vphn_get_nid(i) and
of_node_to_nid_single(cpu) returns NUMA_NO_NODE ? If so,
should we still call node_set_online() below ?


>   node_set_online(nid);
>   }
> 
> -- 
> 2.20.1
> 
--
Thanks and Regards
gautham.

[PATCH v2 2/3] powerpc/numa: Prefer node id queried from vphn

[Srikar Dronamraju]

Node id queried from the static device tree may not
be correct. For example: it may always show 0 on a shared processor.
Hence prefer the node id queried from vphn and fallback on the device tree
based node id if vphn query fails.

Cc: linuxppc-...@lists.ozlabs.org
Cc: linux...@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: Michal Hocko 
Cc: Mel Gorman 
Cc: Vlastimil Babka 
Cc: "Kirill A. Shutemov" 
Cc: Christopher Lameter 
Cc: Michael Ellerman 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Signed-off-by: Srikar Dronamraju 
---
Changelog v1:->v2:
- Rebased to v5.7-rc3

 arch/powerpc/mm/numa.c | 16 
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index b3615b7fdbdf..281531340230 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -719,20 +719,20 @@ static int __init parse_numa_properties(void)
 */
for_each_present_cpu(i) {
struct device_node *cpu;
-   int nid;
-
-   cpu = of_get_cpu_node(i, NULL);
-   BUG_ON(!cpu);
-   nid = of_node_to_nid_single(cpu);
-   of_node_put(cpu);
+   int nid = vphn_get_nid(i);
 
/*
 * Don't fall back to default_nid yet -- we will plug
 * cpus into nodes once the memory scan has discovered
 * the topology.
 */
-   if (nid < 0)
-   continue;
+   if (nid == NUMA_NO_NODE) {
+   cpu = of_get_cpu_node(i, NULL);
+   if (cpu) {
+   nid = of_node_to_nid_single(cpu);
+   of_node_put(cpu);
+   }
+   }
node_set_online(nid);
}
 
-- 
2.20.1