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Diffstat (limited to 'mm/percpu-stats.c')
| -rw-r--r-- | mm/percpu-stats.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c new file mode 100644 index 000000000000..03524a56eeff --- /dev/null +++ b/mm/percpu-stats.c @@ -0,0 +1,222 @@ +/* + * 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); |