[PATCH v2 02/10] powerpc/smp: Merge Power9 topology with Power topology

Srikar Dronamraju
2020-07-21T11:39:01Z

A new sched_domain_topology_level was added just for Power9. However the
same can be achieved by merging powerpc_topology with power9_topology
and makes the code more simpler especially when adding a new sched
domain.

Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Nick Piggin <npiggin@au1.ibm.com>
Cc: Oliver OHalloran <oliveroh@au1.ibm.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Michael Neuling <mikey@linux.ibm.com>
Cc: Anton Blanchard <anton@au1.ibm.com>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.ibm.com>
Cc: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---
Changelog v1 -> v2:
powerpc/smp: Merge Power9 topology with Power topology
Replaced a reference to cpu_smt_mask with per_cpu(cpu_sibling_map, cpu)
since cpu_smt_mask is only defined under CONFIG_SCHED_SMT

arch/powerpc/kernel/smp.c | 33 ++++++++++-----------------------
1 file changed, 10 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 680c0edcc59d..0e0b118d9b6e 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1315,7 +1315,7 @@ int setup_profiling_timer(unsigned int multiplier)
}

#ifdef CONFIG_SCHED_SMT
-/* cpumask of CPUs with asymetric SMT dependancy */
+/* cpumask of CPUs with asymmetric SMT dependency */
static int powerpc_smt_flags(void)
{
int flags = SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES;
@@ -1328,14 +1328,6 @@ static int powerpc_smt_flags(void)
}
#endif

-static struct sched_domain_topology_level powerpc_topology[] = {
-#ifdef CONFIG_SCHED_SMT
- { cpu_smt_mask, powerpc_smt_flags, SD_INIT_NAME(SMT) },
-#endif
- { cpu_cpu_mask, SD_INIT_NAME(DIE) },
- { NULL, },
-};
-
/*
* P9 has a slightly odd architecture where pairs of cores share an L2 cache.
* This topology makes it *much* cheaper to migrate tasks between adjacent cores
@@ -1353,7 +1345,13 @@ static int powerpc_shared_cache_flags(void)
*/
static const struct cpumask *shared_cache_mask(int cpu)
{
- return cpu_l2_cache_mask(cpu);
+ if (shared_caches)
+ return cpu_l2_cache_mask(cpu);
+
+ if (has_big_cores)
+ return cpu_smallcore_mask(cpu);
+
+ return per_cpu(cpu_sibling_map, cpu);
}

#ifdef CONFIG_SCHED_SMT
@@ -1363,7 +1361,7 @@ static const struct cpumask *smallcore_smt_mask(int cpu)
}
#endif

-static struct sched_domain_topology_level power9_topology[] = {
+static struct sched_domain_topology_level powerpc_topology[] = {
#ifdef CONFIG_SCHED_SMT
{ cpu_smt_mask, powerpc_smt_flags, SD_INIT_NAME(SMT) },
#endif
@@ -1388,21 +1386,10 @@ void __init smp_cpus_done(unsigned int max_cpus)
#ifdef CONFIG_SCHED_SMT
if (has_big_cores) {
pr_info("Big cores detected but using small core scheduling\n");
- power9_topology[0].mask = smallcore_smt_mask;
powerpc_topology[0].mask = smallcore_smt_mask;
}
#endif
- /*
- * If any CPU detects that it's sharing a cache with another CPU then
- * use the deeper topology that is aware of this sharing.
- */
- if (shared_caches) {
- pr_info("Using shared cache scheduler topology\n");
- set_sched_topology(power9_topology);
- } else {
- pr_info("Using standard scheduler topology\n");
- set_sched_topology(powerpc_topology);
- }
+ set_sched_topology(powerpc_topology);
}

#ifdef CONFIG_HOTPLUG_CPU
--
2.17.1