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Diffstat (limited to 'mm/percpu-stats.c')
| -rw-r--r-- | mm/percpu-stats.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c new file mode 100644 index 000000000..dd3590dfc --- /dev/null +++ b/mm/percpu-stats.c @@ -0,0 +1,235 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * mm/percpu-debug.c + * + * Copyright (C) 2017 Facebook Inc. + * Copyright (C) 2017 Dennis Zhou <dennis@kernel.org> + * + * 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_chunk_lists[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) +{ + struct pcpu_block_md *chunk_md = &chunk->chunk_md; + 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 / PCPU_MIN_ALLOC_SIZE; + + /* + * 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("first_bit", chunk_md->first_free); + P("free_bytes", chunk->free_bytes); + P("contig_bytes", chunk_md->contig_hint * 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_array(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_chunk_lists[slot], list) { + if (chunk == pcpu_first_chunk) + seq_puts(m, "Chunk: <- First Chunk\n"); + else if (slot == pcpu_to_depopulate_slot) + seq_puts(m, "Chunk (to_depopulate)\n"); + else if (slot == pcpu_sidelined_slot) + seq_puts(m, "Chunk (sidelined):\n"); + else + seq_puts(m, "Chunk:\n"); + chunk_map_stats(m, chunk, buffer); + } + } + + spin_unlock_irq(&pcpu_lock); + + vfree(buffer); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(percpu_stats); + +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); |