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author | Juri Lelli <juri.lelli@arm.com> | 2016-11-06 01:34:31 +0100 |
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committer | Russell King <rmk+kernel@armlinux.org.uk> | 2016-11-22 11:45:08 +0000 |
commit | 7e5930aaef5d4c8664ce4a36b05c63e8b25c1f3f (patch) | |
tree | e914605c839604608c6095c7a71438bffe3f75be /arch/arm/kernel | |
parent | 06073ee26775809f949823ae18a3affd5f376ee0 (diff) | |
download | linux-stable-7e5930aaef5d4c8664ce4a36b05c63e8b25c1f3f.tar.gz linux-stable-7e5930aaef5d4c8664ce4a36b05c63e8b25c1f3f.tar.bz2 linux-stable-7e5930aaef5d4c8664ce4a36b05c63e8b25c1f3f.zip |
ARM: 8622/3: 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
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel')
-rw-r--r-- | arch/arm/kernel/topology.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c index aa63287d9a10..ebf47d91b804 100644 --- a/arch/arm/kernel/topology.c +++ b/arch/arm/kernel/topology.c @@ -22,7 +22,9 @@ #include <linux/of.h> #include <linux/sched.h> #include <linux/slab.h> +#include <linux/string.h> +#include <asm/cpu.h> #include <asm/cputype.h> #include <asm/topology.h> @@ -42,6 +44,7 @@ * updated during this sequence. */ 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) { @@ -53,6 +56,65 @@ 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 + #ifdef CONFIG_OF struct cpu_efficiency { const char *compatible; @@ -132,6 +194,7 @@ 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) { capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT) / capacity_scale; @@ -139,6 +202,7 @@ 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 |