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powerpc/smp: Optimize start_secondary

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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: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-7-srikar@linux.vnet.ibm.com
This commit is contained in:
Srikar Dronamraju 2020-08-10 12:48:30 +05:30 committed by Michael Ellerman
parent f6606cfdfb
commit caa8e29da5
1 changed files with 11 additions and 6 deletions
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17
arch/powerpc/kernel/smp.c
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@ -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)))
shared_caches = true;
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]));