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[/] [test_project/] [trunk/] [linux_sd_driver/] [kernel/] [time/] [timer_stats.c] - Blame information for rev 81

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1 62 marcus.erl
/*
2
 * kernel/time/timer_stats.c
3
 *
4
 * Collect timer usage statistics.
5
 *
6
 * Copyright(C) 2006, Red Hat, Inc., Ingo Molnar
7
 * Copyright(C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
8
 *
9
 * timer_stats is based on timer_top, a similar functionality which was part of
10
 * Con Kolivas dyntick patch set. It was developed by Daniel Petrini at the
11
 * Instituto Nokia de Tecnologia - INdT - Manaus. timer_top's design was based
12
 * on dynamic allocation of the statistics entries and linear search based
13
 * lookup combined with a global lock, rather than the static array, hash
14
 * and per-CPU locking which is used by timer_stats. It was written for the
15
 * pre hrtimer kernel code and therefore did not take hrtimers into account.
16
 * Nevertheless it provided the base for the timer_stats implementation and
17
 * was a helpful source of inspiration. Kudos to Daniel and the Nokia folks
18
 * for this effort.
19
 *
20
 * timer_top.c is
21
 *      Copyright (C) 2005 Instituto Nokia de Tecnologia - INdT - Manaus
22
 *      Written by Daniel Petrini <d.pensator@gmail.com>
23
 *      timer_top.c was released under the GNU General Public License version 2
24
 *
25
 * We export the addresses and counting of timer functions being called,
26
 * the pid and cmdline from the owner process if applicable.
27
 *
28
 * Start/stop data collection:
29
 * # echo 1[0] >/proc/timer_stats
30
 *
31
 * Display the information collected so far:
32
 * # cat /proc/timer_stats
33
 *
34
 * This program is free software; you can redistribute it and/or modify
35
 * it under the terms of the GNU General Public License version 2 as
36
 * published by the Free Software Foundation.
37
 */
38
 
39
#include <linux/proc_fs.h>
40
#include <linux/module.h>
41
#include <linux/spinlock.h>
42
#include <linux/sched.h>
43
#include <linux/seq_file.h>
44
#include <linux/kallsyms.h>
45
 
46
#include <asm/uaccess.h>
47
 
48
/*
49
 * This is our basic unit of interest: a timer expiry event identified
50
 * by the timer, its start/expire functions and the PID of the task that
51
 * started the timer. We count the number of times an event happens:
52
 */
53
struct entry {
54
        /*
55
         * Hash list:
56
         */
57
        struct entry            *next;
58
 
59
        /*
60
         * Hash keys:
61
         */
62
        void                    *timer;
63
        void                    *start_func;
64
        void                    *expire_func;
65
        pid_t                   pid;
66
 
67
        /*
68
         * Number of timeout events:
69
         */
70
        unsigned long           count;
71
        unsigned int            timer_flag;
72
 
73
        /*
74
         * We save the command-line string to preserve
75
         * this information past task exit:
76
         */
77
        char                    comm[TASK_COMM_LEN + 1];
78
 
79
} ____cacheline_aligned_in_smp;
80
 
81
/*
82
 * Spinlock protecting the tables - not taken during lookup:
83
 */
84
static DEFINE_SPINLOCK(table_lock);
85
 
86
/*
87
 * Per-CPU lookup locks for fast hash lookup:
88
 */
89
static DEFINE_PER_CPU(spinlock_t, lookup_lock);
90
 
91
/*
92
 * Mutex to serialize state changes with show-stats activities:
93
 */
94
static DEFINE_MUTEX(show_mutex);
95
 
96
/*
97
 * Collection status, active/inactive:
98
 */
99
static int __read_mostly active;
100
 
101
/*
102
 * Beginning/end timestamps of measurement:
103
 */
104
static ktime_t time_start, time_stop;
105
 
106
/*
107
 * tstat entry structs only get allocated while collection is
108
 * active and never freed during that time - this simplifies
109
 * things quite a bit.
110
 *
111
 * They get freed when a new collection period is started.
112
 */
113
#define MAX_ENTRIES_BITS        10
114
#define MAX_ENTRIES             (1UL << MAX_ENTRIES_BITS)
115
 
116
static unsigned long nr_entries;
117
static struct entry entries[MAX_ENTRIES];
118
 
119
static atomic_t overflow_count;
120
 
121
/*
122
 * The entries are in a hash-table, for fast lookup:
123
 */
124
#define TSTAT_HASH_BITS         (MAX_ENTRIES_BITS - 1)
125
#define TSTAT_HASH_SIZE         (1UL << TSTAT_HASH_BITS)
126
#define TSTAT_HASH_MASK         (TSTAT_HASH_SIZE - 1)
127
 
128
#define __tstat_hashfn(entry)                                           \
129
        (((unsigned long)(entry)->timer       ^                         \
130
          (unsigned long)(entry)->start_func  ^                         \
131
          (unsigned long)(entry)->expire_func ^                         \
132
          (unsigned long)(entry)->pid           ) & TSTAT_HASH_MASK)
133
 
134
#define tstat_hashentry(entry)  (tstat_hash_table + __tstat_hashfn(entry))
135
 
136
static struct entry *tstat_hash_table[TSTAT_HASH_SIZE] __read_mostly;
137
 
138
static void reset_entries(void)
139
{
140
        nr_entries = 0;
141
        memset(entries, 0, sizeof(entries));
142
        memset(tstat_hash_table, 0, sizeof(tstat_hash_table));
143
        atomic_set(&overflow_count, 0);
144
}
145
 
146
static struct entry *alloc_entry(void)
147
{
148
        if (nr_entries >= MAX_ENTRIES)
149
                return NULL;
150
 
151
        return entries + nr_entries++;
152
}
153
 
154
static int match_entries(struct entry *entry1, struct entry *entry2)
155
{
156
        return entry1->timer       == entry2->timer       &&
157
               entry1->start_func  == entry2->start_func  &&
158
               entry1->expire_func == entry2->expire_func &&
159
               entry1->pid         == entry2->pid;
160
}
161
 
162
/*
163
 * Look up whether an entry matching this item is present
164
 * in the hash already. Must be called with irqs off and the
165
 * lookup lock held:
166
 */
167
static struct entry *tstat_lookup(struct entry *entry, char *comm)
168
{
169
        struct entry **head, *curr, *prev;
170
 
171
        head = tstat_hashentry(entry);
172
        curr = *head;
173
 
174
        /*
175
         * The fastpath is when the entry is already hashed,
176
         * we do this with the lookup lock held, but with the
177
         * table lock not held:
178
         */
179
        while (curr) {
180
                if (match_entries(curr, entry))
181
                        return curr;
182
 
183
                curr = curr->next;
184
        }
185
        /*
186
         * Slowpath: allocate, set up and link a new hash entry:
187
         */
188
        prev = NULL;
189
        curr = *head;
190
 
191
        spin_lock(&table_lock);
192
        /*
193
         * Make sure we have not raced with another CPU:
194
         */
195
        while (curr) {
196
                if (match_entries(curr, entry))
197
                        goto out_unlock;
198
 
199
                prev = curr;
200
                curr = curr->next;
201
        }
202
 
203
        curr = alloc_entry();
204
        if (curr) {
205
                *curr = *entry;
206
                curr->count = 0;
207
                curr->next = NULL;
208
                memcpy(curr->comm, comm, TASK_COMM_LEN);
209
 
210
                smp_mb(); /* Ensure that curr is initialized before insert */
211
 
212
                if (prev)
213
                        prev->next = curr;
214
                else
215
                        *head = curr;
216
        }
217
 out_unlock:
218
        spin_unlock(&table_lock);
219
 
220
        return curr;
221
}
222
 
223
/**
224
 * timer_stats_update_stats - Update the statistics for a timer.
225
 * @timer:      pointer to either a timer_list or a hrtimer
226
 * @pid:        the pid of the task which set up the timer
227
 * @startf:     pointer to the function which did the timer setup
228
 * @timerf:     pointer to the timer callback function of the timer
229
 * @comm:       name of the process which set up the timer
230
 *
231
 * When the timer is already registered, then the event counter is
232
 * incremented. Otherwise the timer is registered in a free slot.
233
 */
234
void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
235
                              void *timerf, char *comm,
236
                              unsigned int timer_flag)
237
{
238
        /*
239
         * It doesnt matter which lock we take:
240
         */
241
        spinlock_t *lock;
242
        struct entry *entry, input;
243
        unsigned long flags;
244
 
245
        if (likely(!active))
246
                return;
247
 
248
        lock = &per_cpu(lookup_lock, raw_smp_processor_id());
249
 
250
        input.timer = timer;
251
        input.start_func = startf;
252
        input.expire_func = timerf;
253
        input.pid = pid;
254
        input.timer_flag = timer_flag;
255
 
256
        spin_lock_irqsave(lock, flags);
257
        if (!active)
258
                goto out_unlock;
259
 
260
        entry = tstat_lookup(&input, comm);
261
        if (likely(entry))
262
                entry->count++;
263
        else
264
                atomic_inc(&overflow_count);
265
 
266
 out_unlock:
267
        spin_unlock_irqrestore(lock, flags);
268
}
269
 
270
static void print_name_offset(struct seq_file *m, unsigned long addr)
271
{
272
        char symname[KSYM_NAME_LEN];
273
 
274
        if (lookup_symbol_name(addr, symname) < 0)
275
                seq_printf(m, "<%p>", (void *)addr);
276
        else
277
                seq_printf(m, "%s", symname);
278
}
279
 
280
static int tstats_show(struct seq_file *m, void *v)
281
{
282
        struct timespec period;
283
        struct entry *entry;
284
        unsigned long ms;
285
        long events = 0;
286
        ktime_t time;
287
        int i;
288
 
289
        mutex_lock(&show_mutex);
290
        /*
291
         * If still active then calculate up to now:
292
         */
293
        if (active)
294
                time_stop = ktime_get();
295
 
296
        time = ktime_sub(time_stop, time_start);
297
 
298
        period = ktime_to_timespec(time);
299
        ms = period.tv_nsec / 1000000;
300
 
301
        seq_puts(m, "Timer Stats Version: v0.2\n");
302
        seq_printf(m, "Sample period: %ld.%03ld s\n", period.tv_sec, ms);
303
        if (atomic_read(&overflow_count))
304
                seq_printf(m, "Overflow: %d entries\n",
305
                        atomic_read(&overflow_count));
306
 
307
        for (i = 0; i < nr_entries; i++) {
308
                entry = entries + i;
309
                if (entry->timer_flag & TIMER_STATS_FLAG_DEFERRABLE) {
310
                        seq_printf(m, "%4luD, %5d %-16s ",
311
                                entry->count, entry->pid, entry->comm);
312
                } else {
313
                        seq_printf(m, " %4lu, %5d %-16s ",
314
                                entry->count, entry->pid, entry->comm);
315
                }
316
 
317
                print_name_offset(m, (unsigned long)entry->start_func);
318
                seq_puts(m, " (");
319
                print_name_offset(m, (unsigned long)entry->expire_func);
320
                seq_puts(m, ")\n");
321
 
322
                events += entry->count;
323
        }
324
 
325
        ms += period.tv_sec * 1000;
326
        if (!ms)
327
                ms = 1;
328
 
329
        if (events && period.tv_sec)
330
                seq_printf(m, "%ld total events, %ld.%03ld events/sec\n",
331
                           events, events * 1000 / ms,
332
                           (events * 1000000 / ms) % 1000);
333
        else
334
                seq_printf(m, "%ld total events\n", events);
335
 
336
        mutex_unlock(&show_mutex);
337
 
338
        return 0;
339
}
340
 
341
/*
342
 * After a state change, make sure all concurrent lookup/update
343
 * activities have stopped:
344
 */
345
static void sync_access(void)
346
{
347
        unsigned long flags;
348
        int cpu;
349
 
350
        for_each_online_cpu(cpu) {
351
                spin_lock_irqsave(&per_cpu(lookup_lock, cpu), flags);
352
                /* nothing */
353
                spin_unlock_irqrestore(&per_cpu(lookup_lock, cpu), flags);
354
        }
355
}
356
 
357
static ssize_t tstats_write(struct file *file, const char __user *buf,
358
                            size_t count, loff_t *offs)
359
{
360
        char ctl[2];
361
 
362
        if (count != 2 || *offs)
363
                return -EINVAL;
364
 
365
        if (copy_from_user(ctl, buf, count))
366
                return -EFAULT;
367
 
368
        mutex_lock(&show_mutex);
369
        switch (ctl[0]) {
370
        case '0':
371
                if (active) {
372
                        active = 0;
373
                        time_stop = ktime_get();
374
                        sync_access();
375
                }
376
                break;
377
        case '1':
378
                if (!active) {
379
                        reset_entries();
380
                        time_start = ktime_get();
381
                        smp_mb();
382
                        active = 1;
383
                }
384
                break;
385
        default:
386
                count = -EINVAL;
387
        }
388
        mutex_unlock(&show_mutex);
389
 
390
        return count;
391
}
392
 
393
static int tstats_open(struct inode *inode, struct file *filp)
394
{
395
        return single_open(filp, tstats_show, NULL);
396
}
397
 
398
static struct file_operations tstats_fops = {
399
        .open           = tstats_open,
400
        .read           = seq_read,
401
        .write          = tstats_write,
402
        .llseek         = seq_lseek,
403
        .release        = single_release,
404
};
405
 
406
void __init init_timer_stats(void)
407
{
408
        int cpu;
409
 
410
        for_each_possible_cpu(cpu)
411
                spin_lock_init(&per_cpu(lookup_lock, cpu));
412
}
413
 
414
static int __init init_tstats_procfs(void)
415
{
416
        struct proc_dir_entry *pe;
417
 
418
        pe = create_proc_entry("timer_stats", 0644, NULL);
419
        if (!pe)
420
                return -ENOMEM;
421
 
422
        pe->proc_fops = &tstats_fops;
423
 
424
        return 0;
425
}
426
__initcall(init_tstats_procfs);

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