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);