diff options
Diffstat (limited to 'kernel/time/timer_stats.c')
-rw-r--r-- | kernel/time/timer_stats.c | 425 |
1 files changed, 0 insertions, 425 deletions
diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c deleted file mode 100644 index afddded..0000000 --- a/kernel/time/timer_stats.c +++ /dev/null @@ -1,425 +0,0 @@ -/* - * kernel/time/timer_stats.c - * - * Collect timer usage statistics. - * - * Copyright(C) 2006, Red Hat, Inc., Ingo Molnar - * Copyright(C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com> - * - * timer_stats is based on timer_top, a similar functionality which was part of - * Con Kolivas dyntick patch set. It was developed by Daniel Petrini at the - * Instituto Nokia de Tecnologia - INdT - Manaus. timer_top's design was based - * on dynamic allocation of the statistics entries and linear search based - * lookup combined with a global lock, rather than the static array, hash - * and per-CPU locking which is used by timer_stats. It was written for the - * pre hrtimer kernel code and therefore did not take hrtimers into account. - * Nevertheless it provided the base for the timer_stats implementation and - * was a helpful source of inspiration. Kudos to Daniel and the Nokia folks - * for this effort. - * - * timer_top.c is - * Copyright (C) 2005 Instituto Nokia de Tecnologia - INdT - Manaus - * Written by Daniel Petrini <d.pensator@gmail.com> - * timer_top.c was released under the GNU General Public License version 2 - * - * We export the addresses and counting of timer functions being called, - * the pid and cmdline from the owner process if applicable. - * - * Start/stop data collection: - * # echo [1|0] >/proc/timer_stats - * - * Display the information collected so far: - * # cat /proc/timer_stats - * - * 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/proc_fs.h> -#include <linux/module.h> -#include <linux/spinlock.h> -#include <linux/sched.h> -#include <linux/seq_file.h> -#include <linux/kallsyms.h> - -#include <linux/uaccess.h> - -/* - * This is our basic unit of interest: a timer expiry event identified - * by the timer, its start/expire functions and the PID of the task that - * started the timer. We count the number of times an event happens: - */ -struct entry { - /* - * Hash list: - */ - struct entry *next; - - /* - * Hash keys: - */ - void *timer; - void *start_func; - void *expire_func; - pid_t pid; - - /* - * Number of timeout events: - */ - unsigned long count; - u32 flags; - - /* - * We save the command-line string to preserve - * this information past task exit: - */ - char comm[TASK_COMM_LEN + 1]; - -} ____cacheline_aligned_in_smp; - -/* - * Spinlock protecting the tables - not taken during lookup: - */ -static DEFINE_RAW_SPINLOCK(table_lock); - -/* - * Per-CPU lookup locks for fast hash lookup: - */ -static DEFINE_PER_CPU(raw_spinlock_t, tstats_lookup_lock); - -/* - * Mutex to serialize state changes with show-stats activities: - */ -static DEFINE_MUTEX(show_mutex); - -/* - * Collection status, active/inactive: - */ -int __read_mostly timer_stats_active; - -/* - * Beginning/end timestamps of measurement: - */ -static ktime_t time_start, time_stop; - -/* - * tstat entry structs only get allocated while collection is - * active and never freed during that time - this simplifies - * things quite a bit. - * - * They get freed when a new collection period is started. - */ -#define MAX_ENTRIES_BITS 10 -#define MAX_ENTRIES (1UL << MAX_ENTRIES_BITS) - -static unsigned long nr_entries; -static struct entry entries[MAX_ENTRIES]; - -static atomic_t overflow_count; - -/* - * The entries are in a hash-table, for fast lookup: - */ -#define TSTAT_HASH_BITS (MAX_ENTRIES_BITS - 1) -#define TSTAT_HASH_SIZE (1UL << TSTAT_HASH_BITS) -#define TSTAT_HASH_MASK (TSTAT_HASH_SIZE - 1) - -#define __tstat_hashfn(entry) \ - (((unsigned long)(entry)->timer ^ \ - (unsigned long)(entry)->start_func ^ \ - (unsigned long)(entry)->expire_func ^ \ - (unsigned long)(entry)->pid ) & TSTAT_HASH_MASK) - -#define tstat_hashentry(entry) (tstat_hash_table + __tstat_hashfn(entry)) - -static struct entry *tstat_hash_table[TSTAT_HASH_SIZE] __read_mostly; - -static void reset_entries(void) -{ - nr_entries = 0; - memset(entries, 0, sizeof(entries)); - memset(tstat_hash_table, 0, sizeof(tstat_hash_table)); - atomic_set(&overflow_count, 0); -} - -static struct entry *alloc_entry(void) -{ - if (nr_entries >= MAX_ENTRIES) - return NULL; - - return entries + nr_entries++; -} - -static int match_entries(struct entry *entry1, struct entry *entry2) -{ - return entry1->timer == entry2->timer && - entry1->start_func == entry2->start_func && - entry1->expire_func == entry2->expire_func && - entry1->pid == entry2->pid; -} - -/* - * Look up whether an entry matching this item is present - * in the hash already. Must be called with irqs off and the - * lookup lock held: - */ -static struct entry *tstat_lookup(struct entry *entry, char *comm) -{ - struct entry **head, *curr, *prev; - - head = tstat_hashentry(entry); - curr = *head; - - /* - * The fastpath is when the entry is already hashed, - * we do this with the lookup lock held, but with the - * table lock not held: - */ - while (curr) { - if (match_entries(curr, entry)) - return curr; - - curr = curr->next; - } - /* - * Slowpath: allocate, set up and link a new hash entry: - */ - prev = NULL; - curr = *head; - - raw_spin_lock(&table_lock); - /* - * Make sure we have not raced with another CPU: - */ - while (curr) { - if (match_entries(curr, entry)) - goto out_unlock; - - prev = curr; - curr = curr->next; - } - - curr = alloc_entry(); - if (curr) { - *curr = *entry; - curr->count = 0; - curr->next = NULL; - memcpy(curr->comm, comm, TASK_COMM_LEN); - - smp_mb(); /* Ensure that curr is initialized before insert */ - - if (prev) - prev->next = curr; - else - *head = curr; - } - out_unlock: - raw_spin_unlock(&table_lock); - - return curr; -} - -/** - * timer_stats_update_stats - Update the statistics for a timer. - * @timer: pointer to either a timer_list or a hrtimer - * @pid: the pid of the task which set up the timer - * @startf: pointer to the function which did the timer setup - * @timerf: pointer to the timer callback function of the timer - * @comm: name of the process which set up the timer - * @tflags: The flags field of the timer - * - * When the timer is already registered, then the event counter is - * incremented. Otherwise the timer is registered in a free slot. - */ -void timer_stats_update_stats(void *timer, pid_t pid, void *startf, - void *timerf, char *comm, u32 tflags) -{ - /* - * It doesn't matter which lock we take: - */ - raw_spinlock_t *lock; - struct entry *entry, input; - unsigned long flags; - - if (likely(!timer_stats_active)) - return; - - lock = &per_cpu(tstats_lookup_lock, raw_smp_processor_id()); - - input.timer = timer; - input.start_func = startf; - input.expire_func = timerf; - input.pid = pid; - input.flags = tflags; - - raw_spin_lock_irqsave(lock, flags); - if (!timer_stats_active) - goto out_unlock; - - entry = tstat_lookup(&input, comm); - if (likely(entry)) - entry->count++; - else - atomic_inc(&overflow_count); - - out_unlock: - raw_spin_unlock_irqrestore(lock, flags); -} - -static void print_name_offset(struct seq_file *m, unsigned long addr) -{ - char symname[KSYM_NAME_LEN]; - - if (lookup_symbol_name(addr, symname) < 0) - seq_printf(m, "<%p>", (void *)addr); - else - seq_printf(m, "%s", symname); -} - -static int tstats_show(struct seq_file *m, void *v) -{ - struct timespec64 period; - struct entry *entry; - unsigned long ms; - long events = 0; - ktime_t time; - int i; - - mutex_lock(&show_mutex); - /* - * If still active then calculate up to now: - */ - if (timer_stats_active) - time_stop = ktime_get(); - - time = ktime_sub(time_stop, time_start); - - period = ktime_to_timespec64(time); - ms = period.tv_nsec / 1000000; - - seq_puts(m, "Timer Stats Version: v0.3\n"); - seq_printf(m, "Sample period: %ld.%03ld s\n", (long)period.tv_sec, ms); - if (atomic_read(&overflow_count)) - seq_printf(m, "Overflow: %d entries\n", atomic_read(&overflow_count)); - seq_printf(m, "Collection: %s\n", timer_stats_active ? "active" : "inactive"); - - for (i = 0; i < nr_entries; i++) { - entry = entries + i; - if (entry->flags & TIMER_DEFERRABLE) { - seq_printf(m, "%4luD, %5d %-16s ", - entry->count, entry->pid, entry->comm); - } else { - seq_printf(m, " %4lu, %5d %-16s ", - entry->count, entry->pid, entry->comm); - } - - print_name_offset(m, (unsigned long)entry->start_func); - seq_puts(m, " ("); - print_name_offset(m, (unsigned long)entry->expire_func); - seq_puts(m, ")\n"); - - events += entry->count; - } - - ms += period.tv_sec * 1000; - if (!ms) - ms = 1; - - if (events && period.tv_sec) - seq_printf(m, "%ld total events, %ld.%03ld events/sec\n", - events, events * 1000 / ms, - (events * 1000000 / ms) % 1000); - else - seq_printf(m, "%ld total events\n", events); - - mutex_unlock(&show_mutex); - - return 0; -} - -/* - * After a state change, make sure all concurrent lookup/update - * activities have stopped: - */ -static void sync_access(void) -{ - unsigned long flags; - int cpu; - - for_each_online_cpu(cpu) { - raw_spinlock_t *lock = &per_cpu(tstats_lookup_lock, cpu); - - raw_spin_lock_irqsave(lock, flags); - /* nothing */ - raw_spin_unlock_irqrestore(lock, flags); - } -} - -static ssize_t tstats_write(struct file *file, const char __user *buf, - size_t count, loff_t *offs) -{ - char ctl[2]; - - if (count != 2 || *offs) - return -EINVAL; - - if (copy_from_user(ctl, buf, count)) - return -EFAULT; - - mutex_lock(&show_mutex); - switch (ctl[0]) { - case '0': - if (timer_stats_active) { - timer_stats_active = 0; - time_stop = ktime_get(); - sync_access(); - } - break; - case '1': - if (!timer_stats_active) { - reset_entries(); - time_start = ktime_get(); - smp_mb(); - timer_stats_active = 1; - } - break; - default: - count = -EINVAL; - } - mutex_unlock(&show_mutex); - - return count; -} - -static int tstats_open(struct inode *inode, struct file *filp) -{ - return single_open(filp, tstats_show, NULL); -} - -static const struct file_operations tstats_fops = { - .open = tstats_open, - .read = seq_read, - .write = tstats_write, - .llseek = seq_lseek, - .release = single_release, -}; - -void __init init_timer_stats(void) -{ - int cpu; - - for_each_possible_cpu(cpu) - raw_spin_lock_init(&per_cpu(tstats_lookup_lock, cpu)); -} - -static int __init init_tstats_procfs(void) -{ - struct proc_dir_entry *pe; - - pe = proc_create("timer_stats", 0644, NULL, &tstats_fops); - if (!pe) - return -ENOMEM; - return 0; -} -__initcall(init_tstats_procfs); |