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554 lines
15 KiB
554 lines
15 KiB
/*
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* linux/kernel/profile.c
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* Simple profiling. Manages a direct-mapped profile hit count buffer,
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* with configurable resolution, support for restricting the cpus on
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* which profiling is done, and switching between cpu time and
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* schedule() calls via kernel command line parameters passed at boot.
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*
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* Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
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* Red Hat, July 2004
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* Consolidation of architecture support code for profiling,
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* William Irwin, Oracle, July 2004
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* Amortized hit count accounting via per-cpu open-addressed hashtables
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* to resolve timer interrupt livelocks, William Irwin, Oracle, 2004
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*/
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#include <linux/module.h>
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#include <linux/profile.h>
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#include <linux/bootmem.h>
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#include <linux/notifier.h>
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#include <linux/mm.h>
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#include <linux/cpumask.h>
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#include <linux/cpu.h>
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#include <linux/profile.h>
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#include <linux/highmem.h>
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#include <linux/mutex.h>
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#include <asm/sections.h>
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#include <asm/semaphore.h>
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struct profile_hit {
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u32 pc, hits;
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};
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#define PROFILE_GRPSHIFT 3
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#define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT)
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#define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit))
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#define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ)
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/* Oprofile timer tick hook */
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int (*timer_hook)(struct pt_regs *) __read_mostly;
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static atomic_t *prof_buffer;
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static unsigned long prof_len, prof_shift;
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static int prof_on __read_mostly;
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static cpumask_t prof_cpu_mask = CPU_MASK_ALL;
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#ifdef CONFIG_SMP
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static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
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static DEFINE_PER_CPU(int, cpu_profile_flip);
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static DEFINE_MUTEX(profile_flip_mutex);
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#endif /* CONFIG_SMP */
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static int __init profile_setup(char * str)
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{
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static char __initdata schedstr[] = "schedule";
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int par;
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if (!strncmp(str, schedstr, strlen(schedstr))) {
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prof_on = SCHED_PROFILING;
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if (str[strlen(schedstr)] == ',')
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str += strlen(schedstr) + 1;
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if (get_option(&str, &par))
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prof_shift = par;
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printk(KERN_INFO
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"kernel schedule profiling enabled (shift: %ld)\n",
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prof_shift);
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} else if (get_option(&str, &par)) {
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prof_shift = par;
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prof_on = CPU_PROFILING;
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printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n",
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prof_shift);
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}
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return 1;
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}
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__setup("profile=", profile_setup);
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void __init profile_init(void)
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{
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if (!prof_on)
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return;
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/* only text is profiled */
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prof_len = (_etext - _stext) >> prof_shift;
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prof_buffer = alloc_bootmem(prof_len*sizeof(atomic_t));
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}
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/* Profile event notifications */
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#ifdef CONFIG_PROFILING
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static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
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static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
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static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
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void profile_task_exit(struct task_struct * task)
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{
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blocking_notifier_call_chain(&task_exit_notifier, 0, task);
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}
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int profile_handoff_task(struct task_struct * task)
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{
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int ret;
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ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
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return (ret == NOTIFY_OK) ? 1 : 0;
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}
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void profile_munmap(unsigned long addr)
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{
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blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
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}
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int task_handoff_register(struct notifier_block * n)
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{
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return atomic_notifier_chain_register(&task_free_notifier, n);
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}
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int task_handoff_unregister(struct notifier_block * n)
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{
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return atomic_notifier_chain_unregister(&task_free_notifier, n);
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}
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int profile_event_register(enum profile_type type, struct notifier_block * n)
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{
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int err = -EINVAL;
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switch (type) {
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case PROFILE_TASK_EXIT:
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err = blocking_notifier_chain_register(
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&task_exit_notifier, n);
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break;
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case PROFILE_MUNMAP:
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err = blocking_notifier_chain_register(
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&munmap_notifier, n);
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break;
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}
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return err;
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}
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int profile_event_unregister(enum profile_type type, struct notifier_block * n)
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{
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int err = -EINVAL;
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switch (type) {
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case PROFILE_TASK_EXIT:
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err = blocking_notifier_chain_unregister(
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&task_exit_notifier, n);
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break;
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case PROFILE_MUNMAP:
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err = blocking_notifier_chain_unregister(
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&munmap_notifier, n);
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break;
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}
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return err;
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}
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int register_timer_hook(int (*hook)(struct pt_regs *))
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{
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if (timer_hook)
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return -EBUSY;
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timer_hook = hook;
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return 0;
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}
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void unregister_timer_hook(int (*hook)(struct pt_regs *))
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{
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WARN_ON(hook != timer_hook);
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timer_hook = NULL;
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/* make sure all CPUs see the NULL hook */
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synchronize_sched(); /* Allow ongoing interrupts to complete. */
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}
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EXPORT_SYMBOL_GPL(register_timer_hook);
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EXPORT_SYMBOL_GPL(unregister_timer_hook);
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EXPORT_SYMBOL_GPL(task_handoff_register);
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EXPORT_SYMBOL_GPL(task_handoff_unregister);
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#endif /* CONFIG_PROFILING */
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EXPORT_SYMBOL_GPL(profile_event_register);
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EXPORT_SYMBOL_GPL(profile_event_unregister);
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#ifdef CONFIG_SMP
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/*
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* Each cpu has a pair of open-addressed hashtables for pending
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* profile hits. read_profile() IPI's all cpus to request them
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* to flip buffers and flushes their contents to prof_buffer itself.
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* Flip requests are serialized by the profile_flip_mutex. The sole
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* use of having a second hashtable is for avoiding cacheline
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* contention that would otherwise happen during flushes of pending
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* profile hits required for the accuracy of reported profile hits
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* and so resurrect the interrupt livelock issue.
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*
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* The open-addressed hashtables are indexed by profile buffer slot
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* and hold the number of pending hits to that profile buffer slot on
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* a cpu in an entry. When the hashtable overflows, all pending hits
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* are accounted to their corresponding profile buffer slots with
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* atomic_add() and the hashtable emptied. As numerous pending hits
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* may be accounted to a profile buffer slot in a hashtable entry,
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* this amortizes a number of atomic profile buffer increments likely
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* to be far larger than the number of entries in the hashtable,
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* particularly given that the number of distinct profile buffer
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* positions to which hits are accounted during short intervals (e.g.
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* several seconds) is usually very small. Exclusion from buffer
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* flipping is provided by interrupt disablement (note that for
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* SCHED_PROFILING profile_hit() may be called from process context).
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* The hash function is meant to be lightweight as opposed to strong,
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* and was vaguely inspired by ppc64 firmware-supported inverted
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* pagetable hash functions, but uses a full hashtable full of finite
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* collision chains, not just pairs of them.
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*
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* -- wli
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*/
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static void __profile_flip_buffers(void *unused)
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{
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int cpu = smp_processor_id();
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per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
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}
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static void profile_flip_buffers(void)
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{
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int i, j, cpu;
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mutex_lock(&profile_flip_mutex);
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j = per_cpu(cpu_profile_flip, get_cpu());
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put_cpu();
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on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
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for_each_online_cpu(cpu) {
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struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
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for (i = 0; i < NR_PROFILE_HIT; ++i) {
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if (!hits[i].hits) {
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if (hits[i].pc)
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hits[i].pc = 0;
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continue;
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}
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atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
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hits[i].hits = hits[i].pc = 0;
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}
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}
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mutex_unlock(&profile_flip_mutex);
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}
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static void profile_discard_flip_buffers(void)
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{
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int i, cpu;
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mutex_lock(&profile_flip_mutex);
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i = per_cpu(cpu_profile_flip, get_cpu());
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put_cpu();
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on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
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for_each_online_cpu(cpu) {
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struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
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memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
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}
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mutex_unlock(&profile_flip_mutex);
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}
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void profile_hit(int type, void *__pc)
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{
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unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
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int i, j, cpu;
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struct profile_hit *hits;
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if (prof_on != type || !prof_buffer)
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return;
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pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
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i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
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secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
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cpu = get_cpu();
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hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
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if (!hits) {
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put_cpu();
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return;
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}
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local_irq_save(flags);
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do {
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for (j = 0; j < PROFILE_GRPSZ; ++j) {
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if (hits[i + j].pc == pc) {
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hits[i + j].hits++;
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goto out;
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} else if (!hits[i + j].hits) {
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hits[i + j].pc = pc;
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hits[i + j].hits = 1;
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goto out;
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}
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}
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i = (i + secondary) & (NR_PROFILE_HIT - 1);
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} while (i != primary);
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atomic_inc(&prof_buffer[pc]);
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for (i = 0; i < NR_PROFILE_HIT; ++i) {
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atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
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hits[i].pc = hits[i].hits = 0;
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}
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out:
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local_irq_restore(flags);
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put_cpu();
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}
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#ifdef CONFIG_HOTPLUG_CPU
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static int __devinit profile_cpu_callback(struct notifier_block *info,
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unsigned long action, void *__cpu)
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{
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int node, cpu = (unsigned long)__cpu;
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struct page *page;
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switch (action) {
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case CPU_UP_PREPARE:
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node = cpu_to_node(cpu);
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per_cpu(cpu_profile_flip, cpu) = 0;
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if (!per_cpu(cpu_profile_hits, cpu)[1]) {
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page = alloc_pages_node(node,
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GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
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0);
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if (!page)
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return NOTIFY_BAD;
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per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
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}
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if (!per_cpu(cpu_profile_hits, cpu)[0]) {
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page = alloc_pages_node(node,
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GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
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0);
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if (!page)
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goto out_free;
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per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
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}
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break;
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out_free:
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page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
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per_cpu(cpu_profile_hits, cpu)[1] = NULL;
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__free_page(page);
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return NOTIFY_BAD;
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case CPU_ONLINE:
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cpu_set(cpu, prof_cpu_mask);
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break;
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case CPU_UP_CANCELED:
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case CPU_DEAD:
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cpu_clear(cpu, prof_cpu_mask);
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if (per_cpu(cpu_profile_hits, cpu)[0]) {
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page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
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per_cpu(cpu_profile_hits, cpu)[0] = NULL;
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__free_page(page);
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}
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if (per_cpu(cpu_profile_hits, cpu)[1]) {
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page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
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per_cpu(cpu_profile_hits, cpu)[1] = NULL;
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__free_page(page);
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}
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break;
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}
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return NOTIFY_OK;
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}
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#endif /* CONFIG_HOTPLUG_CPU */
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#else /* !CONFIG_SMP */
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#define profile_flip_buffers() do { } while (0)
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#define profile_discard_flip_buffers() do { } while (0)
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void profile_hit(int type, void *__pc)
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{
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unsigned long pc;
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if (prof_on != type || !prof_buffer)
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return;
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pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
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atomic_inc(&prof_buffer[min(pc, prof_len - 1)]);
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}
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#endif /* !CONFIG_SMP */
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void profile_tick(int type, struct pt_regs *regs)
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{
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if (type == CPU_PROFILING && timer_hook)
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timer_hook(regs);
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if (!user_mode(regs) && cpu_isset(smp_processor_id(), prof_cpu_mask))
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profile_hit(type, (void *)profile_pc(regs));
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}
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#ifdef CONFIG_PROC_FS
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#include <linux/proc_fs.h>
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#include <asm/uaccess.h>
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#include <asm/ptrace.h>
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static int prof_cpu_mask_read_proc (char *page, char **start, off_t off,
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int count, int *eof, void *data)
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{
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int len = cpumask_scnprintf(page, count, *(cpumask_t *)data);
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if (count - len < 2)
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return -EINVAL;
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len += sprintf(page + len, "\n");
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return len;
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}
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static int prof_cpu_mask_write_proc (struct file *file, const char __user *buffer,
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unsigned long count, void *data)
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{
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cpumask_t *mask = (cpumask_t *)data;
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unsigned long full_count = count, err;
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cpumask_t new_value;
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err = cpumask_parse(buffer, count, new_value);
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if (err)
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return err;
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*mask = new_value;
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return full_count;
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}
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void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir)
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{
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struct proc_dir_entry *entry;
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/* create /proc/irq/prof_cpu_mask */
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if (!(entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir)))
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return;
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entry->nlink = 1;
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entry->data = (void *)&prof_cpu_mask;
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entry->read_proc = prof_cpu_mask_read_proc;
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entry->write_proc = prof_cpu_mask_write_proc;
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}
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/*
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* This function accesses profiling information. The returned data is
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* binary: the sampling step and the actual contents of the profile
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* buffer. Use of the program readprofile is recommended in order to
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* get meaningful info out of these data.
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*/
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static ssize_t
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read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
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{
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unsigned long p = *ppos;
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ssize_t read;
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char * pnt;
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unsigned int sample_step = 1 << prof_shift;
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profile_flip_buffers();
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if (p >= (prof_len+1)*sizeof(unsigned int))
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return 0;
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if (count > (prof_len+1)*sizeof(unsigned int) - p)
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count = (prof_len+1)*sizeof(unsigned int) - p;
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read = 0;
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while (p < sizeof(unsigned int) && count > 0) {
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put_user(*((char *)(&sample_step)+p),buf);
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buf++; p++; count--; read++;
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}
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pnt = (char *)prof_buffer + p - sizeof(atomic_t);
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if (copy_to_user(buf,(void *)pnt,count))
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return -EFAULT;
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read += count;
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*ppos += read;
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return read;
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}
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/*
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* Writing to /proc/profile resets the counters
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*
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* Writing a 'profiling multiplier' value into it also re-sets the profiling
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* interrupt frequency, on architectures that support this.
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*/
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static ssize_t write_profile(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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#ifdef CONFIG_SMP
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extern int setup_profiling_timer (unsigned int multiplier);
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if (count == sizeof(int)) {
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unsigned int multiplier;
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if (copy_from_user(&multiplier, buf, sizeof(int)))
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return -EFAULT;
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if (setup_profiling_timer(multiplier))
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return -EINVAL;
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}
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#endif
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profile_discard_flip_buffers();
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memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
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return count;
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}
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static struct file_operations proc_profile_operations = {
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.read = read_profile,
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.write = write_profile,
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};
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#ifdef CONFIG_SMP
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static void __init profile_nop(void *unused)
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{
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}
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static int __init create_hash_tables(void)
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{
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int cpu;
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for_each_online_cpu(cpu) {
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int node = cpu_to_node(cpu);
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struct page *page;
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page = alloc_pages_node(node,
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GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
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0);
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if (!page)
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goto out_cleanup;
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per_cpu(cpu_profile_hits, cpu)[1]
|
|
= (struct profile_hit *)page_address(page);
|
|
page = alloc_pages_node(node,
|
|
GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
|
|
0);
|
|
if (!page)
|
|
goto out_cleanup;
|
|
per_cpu(cpu_profile_hits, cpu)[0]
|
|
= (struct profile_hit *)page_address(page);
|
|
}
|
|
return 0;
|
|
out_cleanup:
|
|
prof_on = 0;
|
|
smp_mb();
|
|
on_each_cpu(profile_nop, NULL, 0, 1);
|
|
for_each_online_cpu(cpu) {
|
|
struct page *page;
|
|
|
|
if (per_cpu(cpu_profile_hits, cpu)[0]) {
|
|
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
|
|
per_cpu(cpu_profile_hits, cpu)[0] = NULL;
|
|
__free_page(page);
|
|
}
|
|
if (per_cpu(cpu_profile_hits, cpu)[1]) {
|
|
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
|
|
per_cpu(cpu_profile_hits, cpu)[1] = NULL;
|
|
__free_page(page);
|
|
}
|
|
}
|
|
return -1;
|
|
}
|
|
#else
|
|
#define create_hash_tables() ({ 0; })
|
|
#endif
|
|
|
|
static int __init create_proc_profile(void)
|
|
{
|
|
struct proc_dir_entry *entry;
|
|
|
|
if (!prof_on)
|
|
return 0;
|
|
if (create_hash_tables())
|
|
return -1;
|
|
if (!(entry = create_proc_entry("profile", S_IWUSR | S_IRUGO, NULL)))
|
|
return 0;
|
|
entry->proc_fops = &proc_profile_operations;
|
|
entry->size = (1+prof_len) * sizeof(atomic_t);
|
|
hotcpu_notifier(profile_cpu_callback, 0);
|
|
return 0;
|
|
}
|
|
module_init(create_proc_profile);
|
|
#endif /* CONFIG_PROC_FS */
|
|
|