power.c
/*
* Performance events - AMD Processor Power Reporting Mechanism
*
* Copyright (C) 2016 Advanced Micro Devices, Inc.
*
* Author: Huang Rui <ray.huang@amd.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/perf_event.h>
#include <asm/cpu_device_id.h>
#include "../perf_event.h"
#define MSR_F15H_CU_PWR_ACCUMULATOR 0xc001007a
#define MSR_F15H_CU_MAX_PWR_ACCUMULATOR 0xc001007b
#define MSR_F15H_PTSC 0xc0010280
/* Event code: LSB 8 bits, passed in attr->config any other bit is reserved. */
#define AMD_POWER_EVENT_MASK 0xFFULL
/*
* Accumulated power status counters.
*/
#define AMD_POWER_EVENTSEL_PKG 1
/*
* The ratio of compute unit power accumulator sample period to the
* PTSC period.
*/
static unsigned int cpu_pwr_sample_ratio;
/* Maximum accumulated power of a compute unit. */
static u64 max_cu_acc_power;
static struct pmu pmu_class;
/*
* Accumulated power represents the sum of each compute unit's (CU) power
* consumption. On any core of each CU we read the total accumulated power from
* MSR_F15H_CU_PWR_ACCUMULATOR. cpu_mask represents CPU bit map of all cores
* which are picked to measure the power for the CUs they belong to.
*/
static cpumask_t cpu_mask;
static void event_update(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
u64 prev_pwr_acc, new_pwr_acc, prev_ptsc, new_ptsc;
u64 delta, tdelta;
prev_pwr_acc = hwc->pwr_acc;
prev_ptsc = hwc->ptsc;
rdmsrl(MSR_F15H_CU_PWR_ACCUMULATOR, new_pwr_acc);
rdmsrl(MSR_F15H_PTSC, new_ptsc);
/*
* Calculate the CU power consumption over a time period, the unit of
* final value (delta) is micro-Watts. Then add it to the event count.
*/
if (new_pwr_acc < prev_pwr_acc) {
delta = max_cu_acc_power + new_pwr_acc;
delta -= prev_pwr_acc;
} else
delta = new_pwr_acc - prev_pwr_acc;
delta *= cpu_pwr_sample_ratio * 1000;
tdelta = new_ptsc - prev_ptsc;
do_div(delta, tdelta);
local64_add(delta, &event->count);
}
static void __pmu_event_start(struct perf_event *event)
{
if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
return;
event->hw.state = 0;
rdmsrl(MSR_F15H_PTSC, event->hw.ptsc);
rdmsrl(MSR_F15H_CU_PWR_ACCUMULATOR, event->hw.pwr_acc);
}
static void pmu_event_start(struct perf_event *event, int mode)
{
__pmu_event_start(event);
}
static void pmu_event_stop(struct perf_event *event, int mode)
{
struct hw_perf_event *hwc = &event->hw;
/* Mark event as deactivated and stopped. */
if (!(hwc->state & PERF_HES_STOPPED))
hwc->state |= PERF_HES_STOPPED;
/* Check if software counter update is necessary. */
if ((mode & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
/*
* Drain the remaining delta count out of an event
* that we are disabling:
*/
event_update(event);
hwc->state |= PERF_HES_UPTODATE;
}
}
static int pmu_event_add(struct perf_event *event, int mode)
{
struct hw_perf_event *hwc = &event->hw;
hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
if (mode & PERF_EF_START)
__pmu_event_start(event);
return 0;
}
static void pmu_event_del(struct perf_event *event, int flags)
{
pmu_event_stop(event, PERF_EF_UPDATE);
}
static int pmu_event_init(struct perf_event *event)
{
u64 cfg = event->attr.config & AMD_POWER_EVENT_MASK;
/* Only look at AMD power events. */
if (event->attr.type != pmu_class.type)
return -ENOENT;
/* Unsupported modes and filters. */
if (event->attr.exclude_user ||
event->attr.exclude_kernel ||
event->attr.exclude_hv ||
event->attr.exclude_idle ||
event->attr.exclude_host ||
event->attr.exclude_guest ||
/* no sampling */
event->attr.sample_period)
return -EINVAL;
if (cfg != AMD_POWER_EVENTSEL_PKG)
return -EINVAL;
return 0;
}
static void pmu_event_read(struct perf_event *event)
{
event_update(event);
}
static ssize_t
get_attr_cpumask(struct device *dev, struct device_attribute *attr, char *buf)
{
return cpumap_print_to_pagebuf(true, buf, &cpu_mask);
}
static DEVICE_ATTR(cpumask, S_IRUGO, get_attr_cpumask, NULL);
static struct attribute *pmu_attrs[] = {
&dev_attr_cpumask.attr,
NULL,
};
static struct attribute_group pmu_attr_group = {
.attrs = pmu_attrs,
};
/*
* Currently it only supports to report the power of each
* processor/package.
*/
EVENT_ATTR_STR(power-pkg, power_pkg, "event=0x01");
EVENT_ATTR_STR(power-pkg.unit, power_pkg_unit, "mWatts");
/* Convert the count from micro-Watts to milli-Watts. */
EVENT_ATTR_STR(power-pkg.scale, power_pkg_scale, "1.000000e-3");
static struct attribute *events_attr[] = {
EVENT_PTR(power_pkg),
EVENT_PTR(power_pkg_unit),
EVENT_PTR(power_pkg_scale),
NULL,
};
static struct attribute_group pmu_events_group = {
.name = "events",
.attrs = events_attr,
};
PMU_FORMAT_ATTR(event, "config:0-7");
static struct attribute *formats_attr[] = {
&format_attr_event.attr,
NULL,
};
static struct attribute_group pmu_format_group = {
.name = "format",
.attrs = formats_attr,
};
static const struct attribute_group *attr_groups[] = {
&pmu_attr_group,
&pmu_format_group,
&pmu_events_group,
NULL,
};
static struct pmu pmu_class = {
.attr_groups = attr_groups,
/* system-wide only */
.task_ctx_nr = perf_invalid_context,
.event_init = pmu_event_init,
.add = pmu_event_add,
.del = pmu_event_del,
.start = pmu_event_start,
.stop = pmu_event_stop,
.read = pmu_event_read,
};
static int power_cpu_exit(unsigned int cpu)
{
int target;
if (!cpumask_test_and_clear_cpu(cpu, &cpu_mask))
return 0;
/*
* Find a new CPU on the same compute unit, if was set in cpumask
* and still some CPUs on compute unit. Then migrate event and
* context to new CPU.
*/
target = cpumask_any_but(topology_sibling_cpumask(cpu), cpu);
if (target < nr_cpumask_bits) {
cpumask_set_cpu(target, &cpu_mask);
perf_pmu_migrate_context(&pmu_class, cpu, target);
}
return 0;
}
static int power_cpu_init(unsigned int cpu)
{
int target;
/*
* 1) If any CPU is set at cpu_mask in the same compute unit, do
* nothing.
* 2) If no CPU is set at cpu_mask in the same compute unit,
* set current ONLINE CPU.
*
* Note: if there is a CPU aside of the new one already in the
* sibling mask, then it is also in cpu_mask.
*/
target = cpumask_any_but(topology_sibling_cpumask(cpu), cpu);
if (target >= nr_cpumask_bits)
cpumask_set_cpu(cpu, &cpu_mask);
return 0;
}
static const struct x86_cpu_id cpu_match[] = {
{ .vendor = X86_VENDOR_AMD, .family = 0x15 },
{},
};
static int __init amd_power_pmu_init(void)
{
int ret;
if (!x86_match_cpu(cpu_match))
return 0;
if (!boot_cpu_has(X86_FEATURE_ACC_POWER))
return -ENODEV;
cpu_pwr_sample_ratio = cpuid_ecx(0x80000007);
if (rdmsrl_safe(MSR_F15H_CU_MAX_PWR_ACCUMULATOR, &max_cu_acc_power)) {
pr_err("Failed to read max compute unit power accumulator MSR\n");
return -ENODEV;
}
cpuhp_setup_state(CPUHP_AP_PERF_X86_AMD_POWER_ONLINE,
"AP_PERF_X86_AMD_POWER_ONLINE",
power_cpu_init, power_cpu_exit);
ret = perf_pmu_register(&pmu_class, "power", -1);
if (WARN_ON(ret)) {
pr_warn("AMD Power PMU registration failed\n");
return ret;
}
pr_info("AMD Power PMU detected\n");
return ret;
}
module_init(amd_power_pmu_init);
static void __exit amd_power_pmu_exit(void)
{
cpuhp_remove_state_nocalls(CPUHP_AP_PERF_X86_AMD_POWER_ONLINE);
perf_pmu_unregister(&pmu_class);
}
module_exit(amd_power_pmu_exit);
MODULE_AUTHOR("Huang Rui <ray.huang@amd.com>");
MODULE_DESCRIPTION("AMD Processor Power Reporting Mechanism");
MODULE_LICENSE("GPL v2");