summaryrefslogtreecommitdiffstats
path: root/mm/percpu-stats.c
blob: ad03d73aa5fed3f1d042450433f3416df70fe678 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
/*
 * mm/percpu-debug.c
 *
 * Copyright (C) 2017		Facebook Inc.
 * Copyright (C) 2017		Dennis Zhou <dennisz@fb.com>
 *
 * This file is released under the GPLv2.
 *
 * Prints statistics about the percpu allocator and backing chunks.
 */
#include <linux/debugfs.h>
#include <linux/list.h>
#include <linux/percpu.h>
#include <linux/seq_file.h>
#include <linux/sort.h>
#include <linux/vmalloc.h>

#include "percpu-internal.h"

#define P(X, Y) \
	seq_printf(m, "  %-20s: %12lld\n", X, (long long int)Y)

struct percpu_stats pcpu_stats;
struct pcpu_alloc_info pcpu_stats_ai;

static int cmpint(const void *a, const void *b)
{
	return *(int *)a - *(int *)b;
}

/*
 * Iterates over all chunks to find the max nr_alloc entries.
 */
static int find_max_nr_alloc(void)
{
	struct pcpu_chunk *chunk;
	int slot, max_nr_alloc;

	max_nr_alloc = 0;
	for (slot = 0; slot < pcpu_nr_slots; slot++)
		list_for_each_entry(chunk, &pcpu_slot[slot], list)
			max_nr_alloc = max(max_nr_alloc, chunk->nr_alloc);

	return max_nr_alloc;
}

/*
 * Prints out chunk state. Fragmentation is considered between
 * the beginning of the chunk to the last allocation.
 *
 * All statistics are in bytes unless stated otherwise.
 */
static void chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk,
			    int *buffer)
{
	int i, last_alloc, as_len, start, end;
	int *alloc_sizes, *p;
	/* statistics */
	int sum_frag = 0, max_frag = 0;
	int cur_min_alloc = 0, cur_med_alloc = 0, cur_max_alloc = 0;

	alloc_sizes = buffer;

	/*
	 * find_last_bit returns the start value if nothing found.
	 * Therefore, we must determine if it is a failure of find_last_bit
	 * and set the appropriate value.
	 */
	last_alloc = find_last_bit(chunk->alloc_map,
				   pcpu_chunk_map_bits(chunk) -
				   chunk->end_offset / PCPU_MIN_ALLOC_SIZE - 1);
	last_alloc = test_bit(last_alloc, chunk->alloc_map) ?
		     last_alloc + 1 : 0;

	as_len = 0;
	start = chunk->start_offset;

	/*
	 * If a bit is set in the allocation map, the bound_map identifies
	 * where the allocation ends.  If the allocation is not set, the
	 * bound_map does not identify free areas as it is only kept accurate
	 * on allocation, not free.
	 *
	 * Positive values are allocations and negative values are free
	 * fragments.
	 */
	while (start < last_alloc) {
		if (test_bit(start, chunk->alloc_map)) {
			end = find_next_bit(chunk->bound_map, last_alloc,
					    start + 1);
			alloc_sizes[as_len] = 1;
		} else {
			end = find_next_bit(chunk->alloc_map, last_alloc,
					    start + 1);
			alloc_sizes[as_len] = -1;
		}

		alloc_sizes[as_len++] *= (end - start) * PCPU_MIN_ALLOC_SIZE;

		start = end;
	}

	/*
	 * The negative values are free fragments and thus sorting gives the
	 * free fragments at the beginning in largest first order.
	 */
	if (as_len > 0) {
		sort(alloc_sizes, as_len, sizeof(int), cmpint, NULL);

		/* iterate through the unallocated fragments */
		for (i = 0, p = alloc_sizes; *p < 0 && i < as_len; i++, p++) {
			sum_frag -= *p;
			max_frag = max(max_frag, -1 * (*p));
		}

		cur_min_alloc = alloc_sizes[i];
		cur_med_alloc = alloc_sizes[(i + as_len - 1) / 2];
		cur_max_alloc = alloc_sizes[as_len - 1];
	}

	P("nr_alloc", chunk->nr_alloc);
	P("max_alloc_size", chunk->max_alloc_size);
	P("empty_pop_pages", chunk->nr_empty_pop_pages);
	P("free_bytes", chunk->free_bytes);
	P("contig_bytes", chunk->contig_bits * PCPU_MIN_ALLOC_SIZE);
	P("sum_frag", sum_frag);
	P("max_frag", max_frag);
	P("cur_min_alloc", cur_min_alloc);
	P("cur_med_alloc", cur_med_alloc);
	P("cur_max_alloc", cur_max_alloc);
	seq_putc(m, '\n');
}

static int percpu_stats_show(struct seq_file *m, void *v)
{
	struct pcpu_chunk *chunk;
	int slot, max_nr_alloc;
	int *buffer;

alloc_buffer:
	spin_lock_irq(&pcpu_lock);
	max_nr_alloc = find_max_nr_alloc();
	spin_unlock_irq(&pcpu_lock);

	/* there can be at most this many free and allocated fragments */
	buffer = vmalloc((2 * max_nr_alloc + 1) * sizeof(int));
	if (!buffer)
		return -ENOMEM;

	spin_lock_irq(&pcpu_lock);

	/* if the buffer allocated earlier is too small */
	if (max_nr_alloc < find_max_nr_alloc()) {
		spin_unlock_irq(&pcpu_lock);
		vfree(buffer);
		goto alloc_buffer;
	}

#define PL(X) \
	seq_printf(m, "  %-20s: %12lld\n", #X, (long long int)pcpu_stats_ai.X)

	seq_printf(m,
			"Percpu Memory Statistics\n"
			"Allocation Info:\n"
			"----------------------------------------\n");
	PL(unit_size);
	PL(static_size);
	PL(reserved_size);
	PL(dyn_size);
	PL(atom_size);
	PL(alloc_size);
	seq_putc(m, '\n');

#undef PL

#define PU(X) \
	seq_printf(m, "  %-20s: %12llu\n", #X, (unsigned long long)pcpu_stats.X)

	seq_printf(m,
			"Global Stats:\n"
			"----------------------------------------\n");
	PU(nr_alloc);
	PU(nr_dealloc);
	PU(nr_cur_alloc);
	PU(nr_max_alloc);
	PU(nr_chunks);
	PU(nr_max_chunks);
	PU(min_alloc_size);
	PU(max_alloc_size);
	P("empty_pop_pages", pcpu_nr_empty_pop_pages);
	seq_putc(m, '\n');

#undef PU

	seq_printf(m,
			"Per Chunk Stats:\n"
			"----------------------------------------\n");

	if (pcpu_reserved_chunk) {
		seq_puts(m, "Chunk: <- Reserved Chunk\n");
		chunk_map_stats(m, pcpu_reserved_chunk, buffer);
	}

	for (slot = 0; slot < pcpu_nr_slots; slot++) {
		list_for_each_entry(chunk, &pcpu_slot[slot], list) {
			if (chunk == pcpu_first_chunk) {
				seq_puts(m, "Chunk: <- First Chunk\n");
				chunk_map_stats(m, chunk, buffer);


			} else {
				seq_puts(m, "Chunk:\n");
				chunk_map_stats(m, chunk, buffer);
			}

		}
	}

	spin_unlock_irq(&pcpu_lock);

	vfree(buffer);

	return 0;
}

static int percpu_stats_open(struct inode *inode, struct file *filp)
{
	return single_open(filp, percpu_stats_show, NULL);
}

static const struct file_operations percpu_stats_fops = {
	.open		= percpu_stats_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static int __init init_percpu_stats_debugfs(void)
{
	debugfs_create_file("percpu_stats", 0444, NULL, NULL,
			&percpu_stats_fops);

	return 0;
}

late_initcall(init_percpu_stats_debugfs);