Commit caa8e29d authored by Srikar Dronamraju's avatar Srikar Dronamraju Committed by Michael Ellerman
Browse files

powerpc/smp: Optimize start_secondary 



In start_secondary, even if shared_cache was already set, system does a
redundant match for cpumask. This redundant check can be removed by
checking if shared_cache is already set.

While here, localize the sibling_mask variable to within the if
condition.

Signed-off-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: default avatarGautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-7-srikar@linux.vnet.ibm.com
parent f6606cfd

arch/powerpc/kernel/smp.c

+11 −6
Original line number Diff line number Diff line
@@ -852,7 +852,7 @@ static int powerpc_shared_cache_flags(void) 
 */

static const struct cpumask *shared_cache_mask(int cpu)

{

	return cpu_l2_cache_mask(cpu);

	return per_cpu(cpu_l2_cache_map, cpu);

}



#ifdef CONFIG_SCHED_SMT
@@ -1319,7 +1319,6 @@ static void add_cpu_to_masks(int cpu) 
void start_secondary(void *unused)

{

	unsigned int cpu = smp_processor_id();

	struct cpumask *(*sibling_mask)(int) = cpu_sibling_mask;



	mmgrab(&init_mm);

	current->active_mm = &init_mm;
@@ -1345,14 +1344,20 @@ void start_secondary(void *unused) 
	/* Update topology CPU masks */

	add_cpu_to_masks(cpu);



	if (has_big_cores)

		sibling_mask = cpu_smallcore_mask;

	/*

	 * Check for any shared caches. Note that this must be done on a

	 * per-core basis because one core in the pair might be disabled.

	 */

	if (!cpumask_equal(cpu_l2_cache_mask(cpu), sibling_mask(cpu)))

	if (!shared_caches) {

		struct cpumask *(*sibling_mask)(int) = cpu_sibling_mask;

		struct cpumask *mask = cpu_l2_cache_mask(cpu);



		if (has_big_cores)

			sibling_mask = cpu_smallcore_mask;



		if (cpumask_weight(mask) > cpumask_weight(sibling_mask(cpu)))

			shared_caches = true;

	}



	set_numa_node(numa_cpu_lookup_table[cpu]);

	set_numa_mem(local_memory_node(numa_cpu_lookup_table[cpu]));