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authorMark Hambleton <mahamble@broadcom.com>2013-11-27 13:30:29 +0000
committerMark Brown <broonie@linaro.org>2013-12-13 13:23:36 +0000
commit8ecd48091c61213762407f5ce02d3fa4ede66402 (patch)
tree3884f06961d61a1f895881c13d97205ce414c0a9
parentd474d10a1a827e0b3402943a62a97d95c0eabf8d (diff)
downloadlinux-linaro-stable-8ecd48091c61213762407f5ce02d3fa4ede66402.tar.gz
arm64: Enable HMP for ARMv8
Signed-off-by: Mark Hambleton <mahamble@broadcom.com> Signed-off-by: Mark Brown <broonie@linaro.org>
-rw-r--r--arch/arm64/Kconfig96
-rw-r--r--arch/arm64/include/asm/topology.h31
-rw-r--r--arch/arm64/kernel/topology.c119
3 files changed, 246 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 2dc43c58923d..195806152794 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -168,6 +168,102 @@ config SCHED_SMT
MultiThreading at a cost of slightly increased overhead in some
places. If unsure say N here.
+config DISABLE_CPU_SCHED_DOMAIN_BALANCE
+ bool "(EXPERIMENTAL) Disable CPU level scheduler load-balancing"
+ help
+ Disables scheduler load-balancing at CPU sched domain level.
+
+config SCHED_HMP
+ bool "(EXPERIMENTAL) Heterogenous multiprocessor scheduling"
+ depends on DISABLE_CPU_SCHED_DOMAIN_BALANCE && SCHED_MC && FAIR_GROUP_SCHED && !SCHED_AUTOGROUP
+ help
+ Experimental scheduler optimizations for heterogeneous platforms.
+ Attempts to introspectively select task affinity to optimize power
+ and performance. Basic support for multiple (>2) cpu types is in place,
+ but it has only been tested with two types of cpus.
+ There is currently no support for migration of task groups, hence
+ !SCHED_AUTOGROUP. Furthermore, normal load-balancing must be disabled
+ between cpus of different type (DISABLE_CPU_SCHED_DOMAIN_BALANCE).
+
+config SCHED_HMP_PRIO_FILTER
+ bool "(EXPERIMENTAL) Filter HMP migrations by task priority"
+ depends on SCHED_HMP
+ help
+ Enables task priority based HMP migration filter. Any task with
+ a NICE value above the threshold will always be on low-power cpus
+ with less compute capacity.
+
+config SCHED_HMP_PRIO_FILTER_VAL
+ int "NICE priority threshold"
+ default 5
+ depends on SCHED_HMP_PRIO_FILTER
+
+config HMP_FAST_CPU_MASK
+ string "HMP scheduler fast CPU mask"
+ depends on SCHED_HMP
+ help
+ Leave empty to use device tree information.
+ Specify the cpuids of the fast CPUs in the system as a list string,
+ e.g. cpuid 0+1 should be specified as 0-1.
+
+config HMP_SLOW_CPU_MASK
+ string "HMP scheduler slow CPU mask"
+ depends on SCHED_HMP
+ help
+ Leave empty to use device tree information.
+ Specify the cpuids of the slow CPUs in the system as a list string,
+ e.g. cpuid 0+1 should be specified as 0-1.
+
+config HMP_VARIABLE_SCALE
+ bool "Allows changing the load tracking scale through sysfs"
+ depends on SCHED_HMP
+ help
+ When turned on, this option exports the thresholds and load average
+ period value for the load tracking patches through sysfs.
+ The values can be modified to change the rate of load accumulation
+ and the thresholds used for HMP migration.
+ The load_avg_period_ms is the time in ms to reach a load average of
+ 0.5 for an idle task of 0 load average ratio that start a busy loop.
+ The up_threshold and down_threshold is the value to go to a faster
+ CPU or to go back to a slower cpu.
+ The {up,down}_threshold are devided by 1024 before being compared
+ to the load average.
+ For examples, with load_avg_period_ms = 128 and up_threshold = 512,
+ a running task with a load of 0 will be migrated to a bigger CPU after
+ 128ms, because after 128ms its load_avg_ratio is 0.5 and the real
+ up_threshold is 0.5.
+ This patch has the same behavior as changing the Y of the load
+ average computation to
+ (1002/1024)^(LOAD_AVG_PERIOD/load_avg_period_ms)
+ but it remove intermadiate overflows in computation.
+
+config HMP_FREQUENCY_INVARIANT_SCALE
+ bool "(EXPERIMENTAL) Frequency-Invariant Tracked Load for HMP"
+ depends on HMP_VARIABLE_SCALE && CPU_FREQ
+ help
+ Scales the current load contribution in line with the frequency
+ of the CPU that the task was executed on.
+ In this version, we use a simple linear scale derived from the
+ maximum frequency reported by CPUFreq.
+ Restricting tracked load to be scaled by the CPU's frequency
+ represents the consumption of possible compute capacity
+ (rather than consumption of actual instantaneous capacity as
+ normal) and allows the HMP migration's simple threshold
+ migration strategy to interact more predictably with CPUFreq's
+ asynchronous compute capacity changes.
+
+config SCHED_HMP_LITTLE_PACKING
+ bool "Small task packing for HMP"
+ depends on SCHED_HMP
+ default n
+ help
+ Allows the HMP Scheduler to pack small tasks into CPUs in the
+ smallest HMP domain.
+ Controlled by two sysfs files in sys/kernel/hmp.
+ packing_enable: 1 to enable, 0 to disable packing. Default 1.
+ packing_limit: runqueue load ratio where a RQ is considered
+ to be full. Default is NICE_0_LOAD * 9/8.
+
config NR_CPUS
int "Maximum number of CPUs (2-32)"
range 2 32
diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
index 611edefaeaf1..983fa7c153a2 100644
--- a/arch/arm64/include/asm/topology.h
+++ b/arch/arm64/include/asm/topology.h
@@ -28,6 +28,37 @@ void store_cpu_topology(unsigned int cpuid);
const struct cpumask *cpu_coregroup_mask(int cpu);
int cluster_to_logical_mask(unsigned int socket_id, cpumask_t *cluster_mask);
+#ifdef CONFIG_DISABLE_CPU_SCHED_DOMAIN_BALANCE
+/* Common values for CPUs */
+#ifndef SD_CPU_INIT
+#define SD_CPU_INIT (struct sched_domain) { \
+ .min_interval = 1, \
+ .max_interval = 4, \
+ .busy_factor = 64, \
+ .imbalance_pct = 125, \
+ .cache_nice_tries = 1, \
+ .busy_idx = 2, \
+ .idle_idx = 1, \
+ .newidle_idx = 0, \
+ .wake_idx = 0, \
+ .forkexec_idx = 0, \
+ \
+ .flags = 0*SD_LOAD_BALANCE \
+ | 1*SD_BALANCE_NEWIDLE \
+ | 1*SD_BALANCE_EXEC \
+ | 1*SD_BALANCE_FORK \
+ | 0*SD_BALANCE_WAKE \
+ | 1*SD_WAKE_AFFINE \
+ | 0*SD_SHARE_CPUPOWER \
+ | 0*SD_SHARE_PKG_RESOURCES \
+ | 0*SD_SERIALIZE \
+ , \
+ .last_balance = jiffies, \
+ .balance_interval = 1, \
+}
+#endif
+#endif /* CONFIG_DISABLE_CPU_SCHED_DOMAIN_BALANCE */
+
#else
static inline void init_cpu_topology(void) { }
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 83d6919d4e0a..971064a0c6b4 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -363,6 +363,125 @@ void store_cpu_topology(unsigned int cpuid)
update_cpu_power(cpuid);
}
+#ifdef CONFIG_SCHED_HMP
+
+/*
+ * Retrieve logical cpu index corresponding to a given MPIDR[23:0]
+ * - mpidr: MPIDR[23:0] to be used for the look-up
+ *
+ * Returns the cpu logical index or -EINVAL on look-up error
+ */
+static inline int get_logical_index(u32 mpidr)
+{
+ int cpu;
+ for (cpu = 0; cpu < nr_cpu_ids; cpu++)
+ if (cpu_logical_map(cpu) == mpidr)
+ return cpu;
+ return -EINVAL;
+}
+
+static const char * const little_cores[] = {
+ "arm,cortex-a53",
+ NULL,
+};
+
+static bool is_little_cpu(struct device_node *cn)
+{
+ const char * const *lc;
+ for (lc = little_cores; *lc; lc++)
+ if (of_device_is_compatible(cn, *lc))
+ return true;
+ return false;
+}
+
+void __init arch_get_fast_and_slow_cpus(struct cpumask *fast,
+ struct cpumask *slow)
+{
+ struct device_node *cn = NULL;
+ int cpu;
+
+ cpumask_clear(fast);
+ cpumask_clear(slow);
+
+ /*
+ * Use the config options if they are given. This helps testing
+ * HMP scheduling on systems without a big.LITTLE architecture.
+ */
+ if (strlen(CONFIG_HMP_FAST_CPU_MASK) && strlen(CONFIG_HMP_SLOW_CPU_MASK)) {
+ if (cpulist_parse(CONFIG_HMP_FAST_CPU_MASK, fast))
+ WARN(1, "Failed to parse HMP fast cpu mask!\n");
+ if (cpulist_parse(CONFIG_HMP_SLOW_CPU_MASK, slow))
+ WARN(1, "Failed to parse HMP slow cpu mask!\n");
+ return;
+ }
+
+ /*
+ * Else, parse device tree for little cores.
+ */
+ while ((cn = of_find_node_by_type(cn, "cpu"))) {
+
+ const u32 *mpidr;
+ int len;
+
+ mpidr = of_get_property(cn, "reg", &len);
+ if (!mpidr || len != 8) {
+ pr_err("%s missing reg property\n", cn->full_name);
+ continue;
+ }
+
+ cpu = get_logical_index(be32_to_cpup(mpidr+1));
+ if (cpu == -EINVAL) {
+ pr_err("couldn't get logical index for mpidr %x\n",
+ be32_to_cpup(mpidr+1));
+ break;
+ }
+
+ if (is_little_cpu(cn))
+ cpumask_set_cpu(cpu, slow);
+ else
+ cpumask_set_cpu(cpu, fast);
+ }
+
+ if (!cpumask_empty(fast) && !cpumask_empty(slow))
+ return;
+
+ /*
+ * We didn't find both big and little cores so let's call all cores
+ * fast as this will keep the system running, with all cores being
+ * treated equal.
+ */
+ cpumask_setall(fast);
+ cpumask_clear(slow);
+}
+
+struct cpumask hmp_slow_cpu_mask;
+
+void __init arch_get_hmp_domains(struct list_head *hmp_domains_list)
+{
+ struct cpumask hmp_fast_cpu_mask;
+ struct hmp_domain *domain;
+
+ arch_get_fast_and_slow_cpus(&hmp_fast_cpu_mask, &hmp_slow_cpu_mask);
+
+ /*
+ * Initialize hmp_domains
+ * Must be ordered with respect to compute capacity.
+ * Fastest domain at head of list.
+ */
+ if(!cpumask_empty(&hmp_slow_cpu_mask)) {
+ domain = (struct hmp_domain *)
+ kmalloc(sizeof(struct hmp_domain), GFP_KERNEL);
+ cpumask_copy(&domain->possible_cpus, &hmp_slow_cpu_mask);
+ cpumask_and(&domain->cpus, cpu_online_mask, &domain->possible_cpus);
+ list_add(&domain->hmp_domains, hmp_domains_list);
+ }
+ domain = (struct hmp_domain *)
+ kmalloc(sizeof(struct hmp_domain), GFP_KERNEL);
+ cpumask_copy(&domain->possible_cpus, &hmp_fast_cpu_mask);
+ cpumask_and(&domain->cpus, cpu_online_mask, &domain->possible_cpus);
+ list_add(&domain->hmp_domains, hmp_domains_list);
+}
+#endif /* CONFIG_SCHED_HMP */
/*
* cluster_to_logical_mask - return cpu logical mask of CPUs in a cluster