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author | Juri Lelli <juri.lelli@arm.com> | 2016-11-03 05:40:18 +0000 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-07 18:15:03 +0000 |
commit | be8f185d8af4dbd450023a42a48c6faa8cbcdfe6 (patch) | |
tree | 0ea5c66f30a48c71ac906b4bc0fd9f96c06b1371 /arch/arm64/kernel/topology.c | |
parent | 7202bde8b7aea7c914e33c7bc2dfb145587f1bdc (diff) | |
download | linux-stable-be8f185d8af4dbd450023a42a48c6faa8cbcdfe6.tar.gz linux-stable-be8f185d8af4dbd450023a42a48c6faa8cbcdfe6.tar.bz2 linux-stable-be8f185d8af4dbd450023a42a48c6faa8cbcdfe6.zip |
arm64: add sysfs cpu_capacity attribute
Add a sysfs cpu_capacity attribute with which it is possible to read and
write (thus over-writing default values) CPUs capacity. This might be
useful in situations where values needs changing after boot.
The new attribute shows up as:
/sys/devices/system/cpu/cpu*/cpu_capacity
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/topology.c')
-rw-r--r-- | arch/arm64/kernel/topology.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index b75b0ba2e113..23e9e13bd2aa 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -20,12 +20,15 @@ #include <linux/of.h> #include <linux/sched.h> #include <linux/slab.h> +#include <linux/string.h> #include <linux/cpufreq.h> +#include <asm/cpu.h> #include <asm/cputype.h> #include <asm/topology.h> static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE; +static DEFINE_MUTEX(cpu_scale_mutex); unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu) { @@ -37,6 +40,65 @@ static void set_capacity_scale(unsigned int cpu, unsigned long capacity) per_cpu(cpu_scale, cpu) = capacity; } +#ifdef CONFIG_PROC_SYSCTL +static ssize_t cpu_capacity_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct cpu *cpu = container_of(dev, struct cpu, dev); + + return sprintf(buf, "%lu\n", + arch_scale_cpu_capacity(NULL, cpu->dev.id)); +} + +static ssize_t cpu_capacity_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t count) +{ + struct cpu *cpu = container_of(dev, struct cpu, dev); + int this_cpu = cpu->dev.id, i; + unsigned long new_capacity; + ssize_t ret; + + if (count) { + ret = kstrtoul(buf, 0, &new_capacity); + if (ret) + return ret; + if (new_capacity > SCHED_CAPACITY_SCALE) + return -EINVAL; + + mutex_lock(&cpu_scale_mutex); + for_each_cpu(i, &cpu_topology[this_cpu].core_sibling) + set_capacity_scale(i, new_capacity); + mutex_unlock(&cpu_scale_mutex); + } + + return count; +} + +static DEVICE_ATTR_RW(cpu_capacity); + +static int register_cpu_capacity_sysctl(void) +{ + int i; + struct device *cpu; + + for_each_possible_cpu(i) { + cpu = get_cpu_device(i); + if (!cpu) { + pr_err("%s: too early to get CPU%d device!\n", + __func__, i); + continue; + } + device_create_file(cpu, &dev_attr_cpu_capacity); + } + + return 0; +} +subsys_initcall(register_cpu_capacity_sysctl); +#endif + static u32 capacity_scale; static u32 *raw_capacity; static bool cap_parsing_failed; @@ -87,6 +149,7 @@ static void normalize_cpu_capacity(void) return; pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale); + mutex_lock(&cpu_scale_mutex); for_each_possible_cpu(cpu) { pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n", cpu, raw_capacity[cpu]); @@ -96,6 +159,7 @@ static void normalize_cpu_capacity(void) pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n", cpu, arch_scale_cpu_capacity(NULL, cpu)); } + mutex_unlock(&cpu_scale_mutex); } #ifdef CONFIG_CPU_FREQ |