Modify the CPU topology policy according to the sched_mc level and the cortex family

Signed-off-by: Vincent Guittot vincent.guittot@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; }