Commit 413e4055 authored by Srikar Dronamraju's avatar Srikar Dronamraju Committed by Michael Ellerman
Browse files

powerpc/numa: Use cpu node map of first sibling thread 



All the sibling threads of a core have to be part of the same node.
To ensure that all the sibling threads map to the same node, always
lookup/update the cpu-to-node map of the first thread in the core.

Signed-off-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Reported-by: default avatarAbdul Haleem <abdhalee@linux.vnet.ibm.com>
Reviewed-by: default avatarNathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200129135301.24739-4-srikar@linux.vnet.ibm.com
parent 76b7bfb1

arch/powerpc/mm/numa.c

+20 −2
Original line number Diff line number Diff line
@@ -467,15 +467,20 @@ static int of_drconf_to_nid_single(struct drmem_lmb *lmb) 
 */

static int numa_setup_cpu(unsigned long lcpu)

{

	int nid = NUMA_NO_NODE;

	struct device_node *cpu;

	int fcpu = cpu_first_thread_sibling(lcpu);

	int nid = NUMA_NO_NODE;



	/*

	 * If a valid cpu-to-node mapping is already available, use it

	 * directly instead of querying the firmware, since it represents

	 * the most recent mapping notified to us by the platform (eg: VPHN).

	 * Since cpu_to_node binding remains the same for all threads in the

	 * core. If a valid cpu-to-node mapping is already available, for

	 * the first thread in the core, use it.

	 */

	if ((nid = numa_cpu_lookup_table[lcpu]) >= 0) {

	nid = numa_cpu_lookup_table[fcpu];

	if (nid >= 0) {

		map_cpu_to_node(lcpu, nid);

		return nid;

	}
@@ -496,6 +501,19 @@ out_present: 
	if (nid < 0 || !node_possible(nid))

		nid = first_online_node;



	/*

	 * Update for the first thread of the core. All threads of a core

	 * have to be part of the same node. This not only avoids querying

	 * for every other thread in the core, but always avoids a case

	 * where virtual node associativity change causes subsequent threads

	 * of a core to be associated with different nid. However if first

	 * thread is already online, expect it to have a valid mapping.

	 */

	if (fcpu != lcpu) {

		WARN_ON(cpu_online(fcpu));

		map_cpu_to_node(fcpu, nid);

	}



	map_cpu_to_node(lcpu, nid);

	of_node_put(cpu);

out:

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