--- /dev/null
+/*
+ * acpi_pad.c ACPI Processor Aggregator Driver
+ *
+ * Copyright (c) 2009, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/cpumask.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+#include <linux/cpu.h>
+#include <linux/tick.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <asm/mwait.h>
+
+#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
+#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
+#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
+static DEFINE_MUTEX(isolated_cpus_lock);
+static DEFINE_MUTEX(round_robin_lock);
+
+static unsigned long power_saving_mwait_eax;
+
+static unsigned char tsc_detected_unstable;
+static unsigned char tsc_marked_unstable;
+
+static void power_saving_mwait_init(void)
+{
+ unsigned int eax, ebx, ecx, edx;
+ unsigned int highest_cstate = 0;
+ unsigned int highest_subcstate = 0;
+ int i;
+
+ if (!boot_cpu_has(X86_FEATURE_MWAIT))
+ return;
+ if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
+ return;
+
+ cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
+
+ if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
+ !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
+ return;
+
+ edx >>= MWAIT_SUBSTATE_SIZE;
+ for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
+ if (edx & MWAIT_SUBSTATE_MASK) {
+ highest_cstate = i;
+ highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
+ }
+ }
+ power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
+ (highest_subcstate - 1);
+
+#if defined(CONFIG_X86)
+ switch (boot_cpu_data.x86_vendor) {
+ case X86_VENDOR_AMD:
+ case X86_VENDOR_INTEL:
+ /*
+ * AMD Fam10h TSC will tick in all
+ * C/P/S0/S1 states when this bit is set.
+ */
+ if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
+ tsc_detected_unstable = 1;
+ break;
+ default:
+ /* TSC could halt in idle */
+ tsc_detected_unstable = 1;
+ }
+#endif
+}
+
+static unsigned long cpu_weight[NR_CPUS];
+static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
+static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
+static void round_robin_cpu(unsigned int tsk_index)
+{
+ struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
+ cpumask_var_t tmp;
+ int cpu;
+ unsigned long min_weight = -1;
+ unsigned long uninitialized_var(preferred_cpu);
+
+ if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
+ return;
+
+ mutex_lock(&round_robin_lock);
+ cpumask_clear(tmp);
+ for_each_cpu(cpu, pad_busy_cpus)
+ cpumask_or(tmp, tmp, topology_thread_cpumask(cpu));
+ cpumask_andnot(tmp, cpu_online_mask, tmp);
+ /* avoid HT sibilings if possible */
+ if (cpumask_empty(tmp))
+ cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
+ if (cpumask_empty(tmp)) {
+ mutex_unlock(&round_robin_lock);
+ return;
+ }
+ for_each_cpu(cpu, tmp) {
+ if (cpu_weight[cpu] < min_weight) {
+ min_weight = cpu_weight[cpu];
+ preferred_cpu = cpu;
+ }
+ }
+
+ if (tsk_in_cpu[tsk_index] != -1)
+ cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
+ tsk_in_cpu[tsk_index] = preferred_cpu;
+ cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
+ cpu_weight[preferred_cpu]++;
+ mutex_unlock(&round_robin_lock);
+
+ set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
+}
+
+static void exit_round_robin(unsigned int tsk_index)
+{
+ struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
+ cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
+ tsk_in_cpu[tsk_index] = -1;
+}
+
+static unsigned int idle_pct = 5; /* percentage */
+static unsigned int round_robin_time = 1; /* second */
+static int power_saving_thread(void *data)
+{
+ struct sched_param param = {.sched_priority = 1};
+ int do_sleep;
+ unsigned int tsk_index = (unsigned long)data;
+ u64 last_jiffies = 0;
+
+ sched_setscheduler(current, SCHED_RR, ¶m);
+
+ while (!kthread_should_stop()) {
+ unsigned long expire_time;
+
+ try_to_freeze();
+
+ /* round robin to cpus */
+ expire_time = last_jiffies + round_robin_time * HZ;
+ if (time_before(expire_time, jiffies)) {
+ last_jiffies = jiffies;
+ round_robin_cpu(tsk_index);
+ }
+
+ do_sleep = 0;
+
+ expire_time = jiffies + HZ * (100 - idle_pct) / 100;
+
+ while (!need_resched()) {
+ if (tsc_detected_unstable && !tsc_marked_unstable) {
+ /* TSC could halt in idle, so notify users */
+ mark_tsc_unstable("TSC halts in idle");
+ tsc_marked_unstable = 1;
+ }
+ local_irq_disable();
+ tick_broadcast_enable();
+ tick_broadcast_enter();
+ stop_critical_timings();
+
+ mwait_idle_with_hints(power_saving_mwait_eax, 1);
+
+ start_critical_timings();
+ tick_broadcast_exit();
+ local_irq_enable();
+
+ if (time_before(expire_time, jiffies)) {
+ do_sleep = 1;
+ break;
+ }
+ }
+
+ /*
+ * current sched_rt has threshold for rt task running time.
+ * When a rt task uses 95% CPU time, the rt thread will be
+ * scheduled out for 5% CPU time to not starve other tasks. But
+ * the mechanism only works when all CPUs have RT task running,
+ * as if one CPU hasn't RT task, RT task from other CPUs will
+ * borrow CPU time from this CPU and cause RT task use > 95%
+ * CPU time. To make 'avoid starvation' work, takes a nap here.
+ */
+ if (unlikely(do_sleep))
+ schedule_timeout_killable(HZ * idle_pct / 100);
+
+ /* If an external event has set the need_resched flag, then
+ * we need to deal with it, or this loop will continue to
+ * spin without calling __mwait().
+ */
+ if (unlikely(need_resched()))
+ schedule();
+ }
+
+ exit_round_robin(tsk_index);
+ return 0;
+}
+
+static struct task_struct *ps_tsks[NR_CPUS];
+static unsigned int ps_tsk_num;
+static int create_power_saving_task(void)
+{
+ int rc;
+
+ ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
+ (void *)(unsigned long)ps_tsk_num,
+ "acpi_pad/%d", ps_tsk_num);
+
+ if (IS_ERR(ps_tsks[ps_tsk_num])) {
+ rc = PTR_ERR(ps_tsks[ps_tsk_num]);
+ ps_tsks[ps_tsk_num] = NULL;
+ } else {
+ rc = 0;
+ ps_tsk_num++;
+ }
+
+ return rc;
+}
+
+static void destroy_power_saving_task(void)
+{
+ if (ps_tsk_num > 0) {
+ ps_tsk_num--;
+ kthread_stop(ps_tsks[ps_tsk_num]);
+ ps_tsks[ps_tsk_num] = NULL;
+ }
+}
+
+static void set_power_saving_task_num(unsigned int num)
+{
+ if (num > ps_tsk_num) {
+ while (ps_tsk_num < num) {
+ if (create_power_saving_task())
+ return;
+ }
+ } else if (num < ps_tsk_num) {
+ while (ps_tsk_num > num)
+ destroy_power_saving_task();
+ }
+}
+
+static void acpi_pad_idle_cpus(unsigned int num_cpus)
+{
+ get_online_cpus();
+
+ num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
+ set_power_saving_task_num(num_cpus);
+
+ put_online_cpus();
+}
+
+static uint32_t acpi_pad_idle_cpus_num(void)
+{
+ return ps_tsk_num;
+}
+
+static ssize_t acpi_pad_rrtime_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ unsigned long num;
+ if (kstrtoul(buf, 0, &num))
+ return -EINVAL;
+ if (num < 1 || num >= 100)
+ return -EINVAL;
+ mutex_lock(&isolated_cpus_lock);
+ round_robin_time = num;
+ mutex_unlock(&isolated_cpus_lock);
+ return count;
+}
+
+static ssize_t acpi_pad_rrtime_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
+}
+static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
+ acpi_pad_rrtime_show,
+ acpi_pad_rrtime_store);
+
+static ssize_t acpi_pad_idlepct_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ unsigned long num;
+ if (kstrtoul(buf, 0, &num))
+ return -EINVAL;
+ if (num < 1 || num >= 100)
+ return -EINVAL;
+ mutex_lock(&isolated_cpus_lock);
+ idle_pct = num;
+ mutex_unlock(&isolated_cpus_lock);
+ return count;
+}
+
+static ssize_t acpi_pad_idlepct_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
+}
+static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
+ acpi_pad_idlepct_show,
+ acpi_pad_idlepct_store);
+
+static ssize_t acpi_pad_idlecpus_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ unsigned long num;
+ if (kstrtoul(buf, 0, &num))
+ return -EINVAL;
+ mutex_lock(&isolated_cpus_lock);
+ acpi_pad_idle_cpus(num);
+ mutex_unlock(&isolated_cpus_lock);
+ return count;
+}
+
+static ssize_t acpi_pad_idlecpus_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return cpumap_print_to_pagebuf(false, buf,
+ to_cpumask(pad_busy_cpus_bits));
+}
+
+static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
+ acpi_pad_idlecpus_show,
+ acpi_pad_idlecpus_store);
+
+static int acpi_pad_add_sysfs(struct acpi_device *device)
+{
+ int result;
+
+ result = device_create_file(&device->dev, &dev_attr_idlecpus);
+ if (result)
+ return -ENODEV;
+ result = device_create_file(&device->dev, &dev_attr_idlepct);
+ if (result) {
+ device_remove_file(&device->dev, &dev_attr_idlecpus);
+ return -ENODEV;
+ }
+ result = device_create_file(&device->dev, &dev_attr_rrtime);
+ if (result) {
+ device_remove_file(&device->dev, &dev_attr_idlecpus);
+ device_remove_file(&device->dev, &dev_attr_idlepct);
+ return -ENODEV;
+ }
+ return 0;
+}
+
+static void acpi_pad_remove_sysfs(struct acpi_device *device)
+{
+ device_remove_file(&device->dev, &dev_attr_idlecpus);
+ device_remove_file(&device->dev, &dev_attr_idlepct);
+ device_remove_file(&device->dev, &dev_attr_rrtime);
+}
+
+/*
+ * Query firmware how many CPUs should be idle
+ * return -1 on failure
+ */
+static int acpi_pad_pur(acpi_handle handle)
+{
+ struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
+ union acpi_object *package;
+ int num = -1;
+
+ if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
+ return num;
+
+ if (!buffer.length || !buffer.pointer)
+ return num;
+
+ package = buffer.pointer;
+
+ if (package->type == ACPI_TYPE_PACKAGE &&
+ package->package.count == 2 &&
+ package->package.elements[0].integer.value == 1) /* rev 1 */
+
+ num = package->package.elements[1].integer.value;
+
+ kfree(buffer.pointer);
+ return num;
+}
+
+static void acpi_pad_handle_notify(acpi_handle handle)
+{
+ int num_cpus;
+ uint32_t idle_cpus;
+ struct acpi_buffer param = {
+ .length = 4,
+ .pointer = (void *)&idle_cpus,
+ };
+
+ mutex_lock(&isolated_cpus_lock);
+ num_cpus = acpi_pad_pur(handle);
+ if (num_cpus < 0) {
+ mutex_unlock(&isolated_cpus_lock);
+ return;
+ }
+ acpi_pad_idle_cpus(num_cpus);
+ idle_cpus = acpi_pad_idle_cpus_num();
+ acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m);
+ mutex_unlock(&isolated_cpus_lock);
+}
+
+static void acpi_pad_notify(acpi_handle handle, u32 event,
+ void *data)
+{
+ struct acpi_device *device = data;
+
+ switch (event) {
+ case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
+ acpi_pad_handle_notify(handle);
+ acpi_bus_generate_netlink_event(device->pnp.device_class,
+ dev_name(&device->dev), event, 0);
+ break;
+ default:
+ pr_warn("Unsupported event [0x%x]\n", event);
+ break;
+ }
+}
+
+static int acpi_pad_add(struct acpi_device *device)
+{
+ acpi_status status;
+
+ strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
+ strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
+
+ if (acpi_pad_add_sysfs(device))
+ return -ENODEV;
+
+ status = acpi_install_notify_handler(device->handle,
+ ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
+ if (ACPI_FAILURE(status)) {
+ acpi_pad_remove_sysfs(device);
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static int acpi_pad_remove(struct acpi_device *device)
+{
+ mutex_lock(&isolated_cpus_lock);
+ acpi_pad_idle_cpus(0);
+ mutex_unlock(&isolated_cpus_lock);
+
+ acpi_remove_notify_handler(device->handle,
+ ACPI_DEVICE_NOTIFY, acpi_pad_notify);
+ acpi_pad_remove_sysfs(device);
+ return 0;
+}
+
+static const struct acpi_device_id pad_device_ids[] = {
+ {"ACPI000C", 0},
+ {"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, pad_device_ids);
+
+static struct acpi_driver acpi_pad_driver = {
+ .name = "processor_aggregator",
+ .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
+ .ids = pad_device_ids,
+ .ops = {
+ .add = acpi_pad_add,
+ .remove = acpi_pad_remove,
+ },
+};
+
+static int __init acpi_pad_init(void)
+{
+ power_saving_mwait_init();
+ if (power_saving_mwait_eax == 0)
+ return -EINVAL;
+
+ return acpi_bus_register_driver(&acpi_pad_driver);
+}
+
+static void __exit acpi_pad_exit(void)
+{
+ acpi_bus_unregister_driver(&acpi_pad_driver);
+}
+
+module_init(acpi_pad_init);
+module_exit(acpi_pad_exit);
+MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
+MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff