All threads of a SMT4 core can either be part of this CPU's l2-cache
mask or not related to this CPU l2-cache mask. Use this relation to
reduce the number of iterations needed to find all the CPUs that share
the same l2-cache.
Use a temporary mask to iterate through the CPUs that may share l2_cache
mask. Also instead of setting one CPU at a time into cpu_l2_cache_mask,
copy the SMT4/sub mask at one shot.
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Cc: LKML <linux-ker...@vger.kernel.org>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Nicholas Piggin <npig...@gmail.com>
Cc: Anton Blanchard <an...@ozlabs.org>
Cc: Oliver O'Halloran <ooh...@gmail.com>
Cc: Nathan Lynch <nath...@linux.ibm.com>
Cc: Michael Neuling <mi...@neuling.org>
Cc: Gautham R Shenoy <e...@linux.vnet.ibm.com>
Cc: Satheesh Rajendran <sathn...@linux.vnet.ibm.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Valentin Schneider <valentin.schnei...@arm.com>
Signed-off-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
---
arch/powerpc/kernel/smp.c | 51 ++++++++++++++++++++++++++++++++++-----
1 file changed, 45 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 6f866e6b12f8..17e90c2414af 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -670,6 +670,28 @@ static void set_cpus_unrelated(int i, int j,
}
#endif
+/*
+ * Extends set_cpus_related. Instead of setting one CPU at a time in
+ * dstmask, set srcmask at oneshot. dstmask should be super set of srcmask.
+ */
+static void or_cpumasks_related(int i, int j, struct cpumask *(*srcmask)(int),
+ struct cpumask *(*dstmask)(int))
+{
+ struct cpumask *mask;
+ int k;
+
+ mask = srcmask(j);
+ for_each_cpu(k, srcmask(i))
+ cpumask_or(dstmask(k), dstmask(k), mask);
+
+ if (i == j)
+ return;
+
+ mask = srcmask(i);
+ for_each_cpu(k, srcmask(j))
+ cpumask_or(dstmask(k), dstmask(k), mask);
+}
+
/*
* parse_thread_groups: Parses the "ibm,thread-groups" device tree
* property for the CPU device node @dn and stores
@@ -1220,7 +1242,9 @@ static struct device_node *cpu_to_l2cache(int cpu)
static bool update_mask_by_l2(int cpu)
{
+ struct cpumask *(*submask_fn)(int) = cpu_sibling_mask;
struct device_node *l2_cache, *np;
+ cpumask_var_t mask;
int i;
l2_cache = cpu_to_l2cache(cpu);
@@ -1240,22 +1264,37 @@ static bool update_mask_by_l2(int cpu)
return false;
}
- cpumask_set_cpu(cpu, cpu_l2_cache_mask(cpu));
- for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
+ alloc_cpumask_var_node(&mask, GFP_KERNEL, cpu_to_node(cpu));
+ cpumask_and(mask, cpu_online_mask, cpu_cpu_mask(cpu));
+
+ if (has_big_cores)
+ submask_fn = cpu_smallcore_mask;
+
+ /* Update l2-cache mask with all the CPUs that are part of submask */
+ or_cpumasks_related(cpu, cpu, submask_fn, cpu_l2_cache_mask);
+
+ /* Skip all CPUs already part of current CPU l2-cache mask */
+ cpumask_andnot(mask, mask, cpu_l2_cache_mask(cpu));
+
+ for_each_cpu(i, mask) {
/*
* when updating the marks the current CPU has not been marked
* online, but we need to update the cache masks
*/
np = cpu_to_l2cache(i);
- if (!np)
- continue;
- if (np == l2_cache)
- set_cpus_related(cpu, i, cpu_l2_cache_mask);
+ /* Skip all CPUs already part of current CPU l2-cache */
+ if (np == l2_cache) {
+ or_cpumasks_related(cpu, i, submask_fn,
cpu_l2_cache_mask);
+ cpumask_andnot(mask, mask, submask_fn(i));
+ } else {
+ cpumask_andnot(mask, mask, cpu_l2_cache_mask(i));
+ }
of_node_put(np);
}
of_node_put(l2_cache);
+ free_cpumask_var(mask);
return true;
}
--
2.17.1
