Modify the CPU topology policy according to the sched_mc level and the cortex
family
Signed-off-by: Vincent Guittot <vincent.guit...@linaro.org>
---
arch/arm/kernel/topology.c | 80 +++++++++++++++++++++++++++++++++++++++++--
1 files changed, 76 insertions(+), 4 deletions(-)
diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
index 90352cb..af1c3e6 100644
--- a/arch/arm/kernel/topology.c
+++ b/arch/arm/kernel/topology.c
@@ -18,6 +18,7 @@
#include <linux/node.h>
#include <linux/nodemask.h>
#include <linux/sched.h>
+#include <linux/cpumask.h>
#include <asm/cputype.h>
#include <asm/topology.h>
@@ -47,7 +48,7 @@ struct cputopo_arm cpu_topology[NR_CPUS];
* cpu topology mask management
*/
-unsigned int advanced_topology = 0;
+unsigned int advanced_topology = 1;
/*
* default topology function
@@ -113,6 +114,74 @@ static void normal_cpu_topology_mask(void)
}
/*
+ * For Cortex-A9 MPcore, we emulate a multi-package topology in power mode.
+ * The goal is to gathers tasks on 1 virtual package
+ */
+static void power_cpu_topology_mask_CA9(void)
+{
+
+ unsigned int cpuid, cpu;
+
+ for_each_possible_cpu(cpuid) {
+ struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid];
+
+ for_each_possible_cpu(cpu) {
+ struct cputopo_arm *cpu_topo = &cpu_topology[cpu];
+
+ if ((cpuid_topo->socket_id == cpu_topo->socket_id)
+ && ((cpuid & 0x1) == (cpu & 0x1))) {
+ cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
+ if (cpu != cpuid)
+ cpumask_set_cpu(cpu,
+ &cpuid_topo->core_sibling);
+
+ if (cpuid_topo->core_id == cpu_topo->core_id) {
+ cpumask_set_cpu(cpuid,
+ &cpu_topo->thread_sibling);
+ if (cpu != cpuid)
+ cpumask_set_cpu(cpu,
+
&cpuid_topo->thread_sibling);
+ }
+ }
+ }
+ }
+ smp_wmb();
+}
+
+#define ARM_FAMILY_MASK 0xFF0FFFF0
+#define ARM_CORTEX_A9_FAMILY 0x410FC090
+
+/* update_cpu_topology_policy select a cpu topology policy according to the
+ * available cores.
+ * TODO: The current version assumes that all cores are exactly the same which
+ * might not be true. We need to update it to take into account various
+ * configuration among which system with different kind of core.
+ */
+static int update_cpu_topology_policy(void)
+{
+ unsigned long cpuid;
+
+ if (sched_mc_power_savings == POWERSAVINGS_BALANCE_NONE) {
+ set_cpu_topology_mask = normal_cpu_topology_mask;
+ return 0;
+ }
+
+ cpuid = read_cpuid_id();
+ cpuid &= ARM_FAMILY_MASK;
+
+ switch (cpuid) {
+ case ARM_CORTEX_A9_FAMILY:
+ set_cpu_topology_mask = power_cpu_topology_mask_CA9;
+ break;
+ default:
+ set_cpu_topology_mask = normal_cpu_topology_mask;
+ break;
+ }
+
+ return 0;
+}
+
+/*
* store_cpu_topology is called at boot when only one cpu is running
* and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
* which prevents simultaneous write access to cpu_topology array
@@ -183,11 +252,14 @@ int arch_update_cpu_topology(void)
if (!advanced_topology)
return 0;
- /* clear core mask */
+ /* clear core threads mask */
clear_cpu_topology_mask();
- /* update core and thread sibling masks */
- normal_cpu_topology_mask();
+ /* set topology policy */
+ update_cpu_topology_policy();
+
+ /* set topology mask*/
+ (*set_cpu_topology_mask)();
return 1;
}
--
1.7.4.1
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