summaryrefslogtreecommitdiffstats
path: root/mm/percpu-stats.c
blob: 32f3550ea09940d7d6cd9a3e36e1c31507eddc6c (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
/*
 * 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 # of map entries used.
 */
static int find_max_map_used(void)
{
	struct pcpu_chunk *chunk;
	int slot, max_map_used;

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

	return max_map_used;
}

/*
 * Prints out chunk state. Fragmentation is considered between
 * the beginning of the chunk to the last allocation.
 */
static void chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk,
			    int *buffer)
{
	int i, s_index, last_alloc, alloc_sign, as_len;
	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;
	s_index = (chunk->start_offset) ? 1 : 0;

	/* find last allocation */
	last_alloc = -1;
	for (i = chunk->map_used - 1; i >= s_index; i--) {
		if (chunk->map[i] & 1) {
			last_alloc = i;
			break;
		}
	}

	/* if the chunk is not empty - ignoring reserve */
	if (last_alloc >= s_index) {
		as_len = last_alloc + 1 - s_index;

		/*
		 * Iterate through chunk map computing size info.
		 * The first bit is overloaded to be a used flag.
		 * negative = free space, positive = allocated
		 */
		for (i = 0, p = chunk->map + s_index; i < as_len; i++, p++) {
			alloc_sign = (*p & 1) ? 1 : -1;
			alloc_sizes[i] = alloc_sign *
				((p[1] & ~1) - (p[0] & ~1));
		}

		sort(alloc_sizes, as_len, sizeof(chunk->map[0]), cmpint, NULL);

		/* Iterate through the unallocated fragements. */
		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("free_size", chunk->free_size);
	P("contig_hint", chunk->contig_hint);
	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_map_used;
	int *buffer;

alloc_buffer:
	spin_lock_irq(&pcpu_lock);
	max_map_used = find_max_map_used();
	spin_unlock_irq(&pcpu_lock);

	buffer = vmalloc(max_map_used * sizeof(pcpu_first_chunk->map[0]));
	if (!buffer)
		return -ENOMEM;

	spin_lock_irq(&pcpu_lock);

	/* if the buffer allocated earlier is too small */
	if (max_map_used < find_max_map_used()) {
		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);