![Ingo Molnar](/assets/img/avatar_default.png)
There was lots of #ifdef noise in the kernel due to hotcpu_notifier(fn, prio) not correctly marking 'fn' as used in the !HOTPLUG_CPU case, and thus generating compiler warnings of unused symbols, hence forcing people to add #ifdefs. the compiler can skip truly unused functions just fine: text data bss dec hex filename 1624412 728710 3674856 6027978 5bfaca vmlinux.before 1624412 728710 3674856 6027978 5bfaca vmlinux.after [akpm@osdl.org: topology.c fix] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
183 lines
5.7 KiB
C
183 lines
5.7 KiB
C
/*
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* linux/arch/i386/kerne/cpu/mcheck/therm_throt.c
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*
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* Thermal throttle event support code (such as syslog messaging and rate
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* limiting) that was factored out from x86_64 (mce_intel.c) and i386 (p4.c).
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* This allows consistent reporting of CPU thermal throttle events.
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*
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* Maintains a counter in /sys that keeps track of the number of thermal
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* events, such that the user knows how bad the thermal problem might be
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* (since the logging to syslog and mcelog is rate limited).
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*
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* Author: Dmitriy Zavin (dmitriyz@google.com)
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*
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* Credits: Adapted from Zwane Mwaikambo's original code in mce_intel.c.
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* Inspired by Ross Biro's and Al Borchers' counter code.
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*/
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#include <linux/percpu.h>
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#include <linux/sysdev.h>
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#include <linux/cpu.h>
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#include <asm/cpu.h>
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#include <linux/notifier.h>
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#include <linux/jiffies.h>
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#include <asm/therm_throt.h>
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/* How long to wait between reporting thermal events */
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#define CHECK_INTERVAL (300 * HZ)
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static DEFINE_PER_CPU(__u64, next_check) = INITIAL_JIFFIES;
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static DEFINE_PER_CPU(unsigned long, thermal_throttle_count);
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atomic_t therm_throt_en = ATOMIC_INIT(0);
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#ifdef CONFIG_SYSFS
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#define define_therm_throt_sysdev_one_ro(_name) \
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static SYSDEV_ATTR(_name, 0444, therm_throt_sysdev_show_##_name, NULL)
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#define define_therm_throt_sysdev_show_func(name) \
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static ssize_t therm_throt_sysdev_show_##name(struct sys_device *dev, \
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char *buf) \
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{ \
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unsigned int cpu = dev->id; \
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ssize_t ret; \
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\
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preempt_disable(); /* CPU hotplug */ \
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if (cpu_online(cpu)) \
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ret = sprintf(buf, "%lu\n", \
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per_cpu(thermal_throttle_##name, cpu)); \
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else \
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ret = 0; \
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preempt_enable(); \
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\
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return ret; \
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}
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define_therm_throt_sysdev_show_func(count);
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define_therm_throt_sysdev_one_ro(count);
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static struct attribute *thermal_throttle_attrs[] = {
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&attr_count.attr,
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NULL
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};
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static struct attribute_group thermal_throttle_attr_group = {
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.attrs = thermal_throttle_attrs,
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.name = "thermal_throttle"
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};
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#endif /* CONFIG_SYSFS */
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/***
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* therm_throt_process - Process thermal throttling event from interrupt
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* @curr: Whether the condition is current or not (boolean), since the
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* thermal interrupt normally gets called both when the thermal
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* event begins and once the event has ended.
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*
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* This function is called by the thermal interrupt after the
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* IRQ has been acknowledged.
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*
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* It will take care of rate limiting and printing messages to the syslog.
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*
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* Returns: 0 : Event should NOT be further logged, i.e. still in
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* "timeout" from previous log message.
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* 1 : Event should be logged further, and a message has been
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* printed to the syslog.
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*/
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int therm_throt_process(int curr)
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{
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unsigned int cpu = smp_processor_id();
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__u64 tmp_jiffs = get_jiffies_64();
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if (curr)
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__get_cpu_var(thermal_throttle_count)++;
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if (time_before64(tmp_jiffs, __get_cpu_var(next_check)))
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return 0;
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__get_cpu_var(next_check) = tmp_jiffs + CHECK_INTERVAL;
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/* if we just entered the thermal event */
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if (curr) {
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printk(KERN_CRIT "CPU%d: Temperature above threshold, "
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"cpu clock throttled (total events = %lu)\n", cpu,
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__get_cpu_var(thermal_throttle_count));
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add_taint(TAINT_MACHINE_CHECK);
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} else {
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printk(KERN_CRIT "CPU%d: Temperature/speed normal\n", cpu);
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}
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return 1;
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}
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#ifdef CONFIG_SYSFS
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/* Add/Remove thermal_throttle interface for CPU device */
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static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev)
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{
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return sysfs_create_group(&sys_dev->kobj, &thermal_throttle_attr_group);
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}
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static __cpuinit void thermal_throttle_remove_dev(struct sys_device *sys_dev)
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{
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return sysfs_remove_group(&sys_dev->kobj, &thermal_throttle_attr_group);
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}
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/* Mutex protecting device creation against CPU hotplug */
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static DEFINE_MUTEX(therm_cpu_lock);
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/* Get notified when a cpu comes on/off. Be hotplug friendly. */
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static __cpuinit int thermal_throttle_cpu_callback(struct notifier_block *nfb,
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unsigned long action,
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void *hcpu)
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{
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unsigned int cpu = (unsigned long)hcpu;
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struct sys_device *sys_dev;
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int err;
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sys_dev = get_cpu_sysdev(cpu);
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mutex_lock(&therm_cpu_lock);
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switch (action) {
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case CPU_ONLINE:
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err = thermal_throttle_add_dev(sys_dev);
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WARN_ON(err);
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break;
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case CPU_DEAD:
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thermal_throttle_remove_dev(sys_dev);
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break;
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}
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mutex_unlock(&therm_cpu_lock);
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return NOTIFY_OK;
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}
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static struct notifier_block thermal_throttle_cpu_notifier =
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{
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.notifier_call = thermal_throttle_cpu_callback,
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};
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static __init int thermal_throttle_init_device(void)
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{
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unsigned int cpu = 0;
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int err;
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if (!atomic_read(&therm_throt_en))
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return 0;
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register_hotcpu_notifier(&thermal_throttle_cpu_notifier);
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#ifdef CONFIG_HOTPLUG_CPU
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mutex_lock(&therm_cpu_lock);
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#endif
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/* connect live CPUs to sysfs */
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for_each_online_cpu(cpu) {
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err = thermal_throttle_add_dev(get_cpu_sysdev(cpu));
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WARN_ON(err);
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}
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#ifdef CONFIG_HOTPLUG_CPU
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mutex_unlock(&therm_cpu_lock);
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#endif
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return 0;
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}
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device_initcall(thermal_throttle_init_device);
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#endif /* CONFIG_SYSFS */
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