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/*
* 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, " %-24s: %8lld\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,
void *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->has_reserved ? 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;
void *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, " %-24s: %8lld\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, " %-18s: %14llu\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);
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);
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