Commit 48b63961 authored by Oscar Salvador's avatar Oscar Salvador Committed by Michael Ellerman
Browse files

powerpc/numa: Associate numa node to its cpu earlier 



powerpc is the only platform that do not rely on
cpu_up()->try_online_node() to bring up a numa node,
and special cases it, instead, deep in its own machinery:

dlpar_online_cpu
 find_and_online_cpu_nid
  try_online_node

This should not be needed, but the thing is that the try_online_node()
from cpu_up() will not apply on the right node, because cpu_to_node()
will return the old mapping numa<->cpu that gets set on boot stage
for all possible cpus.

That can be seen easily if we try to print out the numa node passed
to try_online_node() in cpu_up().

The thing is that the numa<->cpu mapping does not get updated till a much
later stage in start_secondary:

start_secondary:
 set_numa_node(numa_cpu_lookup_table[cpu])

But we do not really care, as we already now the
CPU <-> NUMA associativity back in find_and_online_cpu_nid(),
so let us make use of that and set the proper numa<->cpu mapping,
so cpu_to_node() in cpu_up() returns the right node and
try_online_node() can do its work.

Signed-off-by: default avatarOscar Salvador <osalvador@suse.de>
Tested-by: default avatarGeetika Moolchandani <Geetika.Moolchandani1@ibm.com>
Reviewed-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220411074934.4632-1-osalvador@suse.de
parent 9a9c5ff5

arch/powerpc/include/asm/topology.h

+2 −6
Original line number Diff line number Diff line
@@ -111,14 +111,10 @@ static inline void unmap_cpu_from_node(unsigned long cpu) {} 
#endif /* CONFIG_NUMA */



#if defined(CONFIG_NUMA) && defined(CONFIG_PPC_SPLPAR)

extern int find_and_online_cpu_nid(int cpu);

void find_and_update_cpu_nid(int cpu);

extern int cpu_to_coregroup_id(int cpu);

#else

static inline int find_and_online_cpu_nid(int cpu)

{

	return 0;

}



static inline void find_and_update_cpu_nid(int cpu) {}

static inline int cpu_to_coregroup_id(int cpu)

{

#ifdef CONFIG_SMP

arch/powerpc/mm/numa.c

+8 −24
Original line number Diff line number Diff line
@@ -1422,42 +1422,26 @@ static long vphn_get_associativity(unsigned long cpu, 
	return rc;

}



int find_and_online_cpu_nid(int cpu)

void find_and_update_cpu_nid(int cpu)

{

	__be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};

	int new_nid;



	/* Use associativity from first thread for all siblings */

	if (vphn_get_associativity(cpu, associativity))

		return cpu_to_node(cpu);

		return;



	/* Do not have previous associativity, so find it now. */

	new_nid = associativity_to_nid(associativity);

	if (new_nid < 0 || !node_possible(new_nid))

		new_nid = first_online_node;



	if (!node_online(new_nid)) {

#ifdef CONFIG_MEMORY_HOTPLUG

		/*

		 * Need to ensure that NODE_DATA is initialized for a node from

		 * available memory (see memblock_alloc_try_nid). If unable to

		 * init the node, then default to nearest node that has memory

		 * installed. Skip onlining a node if the subsystems are not

		 * yet initialized.

		 */

		if (!topology_inited || try_online_node(new_nid))

			new_nid = first_online_node;

#else

		/*

		 * Default to using the nearest node that has memory installed.

		 * Otherwise, it would be necessary to patch the kernel MM code

		 * to deal with more memoryless-node error conditions.

		 */

	if (new_nid < 0 || !node_possible(new_nid))

		new_nid = first_online_node;

#endif

	}

	else

		// Associate node <-> cpu, so cpu_up() calls

		// try_online_node() on the right node.

		set_cpu_numa_node(cpu, new_nid);



	pr_debug("%s:%d cpu %d nid %d\n", __func__, __LINE__, cpu, new_nid);

	return new_nid;

}



int cpu_to_coregroup_id(int cpu)

arch/powerpc/platforms/pseries/hotplug-cpu.c

+1 −1
Original line number Diff line number Diff line
@@ -398,7 +398,7 @@ static int dlpar_online_cpu(struct device_node *dn) 
			if (get_hard_smp_processor_id(cpu) != thread)

				continue;

			cpu_maps_update_done();

			find_and_online_cpu_nid(cpu);

			find_and_update_cpu_nid(cpu);

			rc = device_online(get_cpu_device(cpu));

			if (rc) {

				dlpar_offline_cpu(dn);