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-rw-r--r--mm/Kconfig8
-rw-r--r--mm/Makefile1
-rw-r--r--mm/percpu-internal.h131
-rw-r--r--mm/percpu-km.c4
-rw-r--r--mm/percpu-stats.c222
-rw-r--r--mm/percpu-vm.c5
-rw-r--r--mm/percpu.c9
7 files changed, 380 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index beb7a455915d..8fae42606d56 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -706,3 +706,11 @@ config ARCH_USES_HIGH_VMA_FLAGS
bool
config ARCH_HAS_PKEYS
bool
+
+config PERCPU_STATS
+ bool "Collect percpu memory statistics"
+ default n
+ help
+ This feature collects and exposes statistics via debugfs. The
+ information includes global and per chunk statistics, which can
+ be used to help understand percpu memory usage.
diff --git a/mm/Makefile b/mm/Makefile
index 026f6a828a50..411bd24d4a7c 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -103,3 +103,4 @@ obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o
obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o
obj-$(CONFIG_DEBUG_PAGE_REF) += debug_page_ref.o
obj-$(CONFIG_HARDENED_USERCOPY) += usercopy.o
+obj-$(CONFIG_PERCPU_STATS) += percpu-stats.o
diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h
index 68bf18522a6d..d030fce745a2 100644
--- a/mm/percpu-internal.h
+++ b/mm/percpu-internal.h
@@ -5,6 +5,11 @@
#include <linux/percpu.h>
struct pcpu_chunk {
+#ifdef CONFIG_PERCPU_STATS
+ int nr_alloc; /* # of allocations */
+ size_t max_alloc_size; /* largest allocation size */
+#endif
+
struct list_head list; /* linked to pcpu_slot lists */
int free_size; /* free bytes in the chunk */
int contig_hint; /* max contiguous size hint */
@@ -18,6 +23,11 @@ struct pcpu_chunk {
void *data; /* chunk data */
int first_free; /* no free below this */
bool immutable; /* no [de]population allowed */
+ bool has_reserved; /* Indicates if chunk has reserved space
+ at the beginning. Reserved chunk will
+ contain reservation for static chunk.
+ Dynamic chunk will contain reservation
+ for static and reserved chunks. */
int nr_populated; /* # of populated pages */
unsigned long populated[]; /* populated bitmap */
};
@@ -30,4 +40,125 @@ extern int pcpu_nr_slots;
extern struct pcpu_chunk *pcpu_first_chunk;
extern struct pcpu_chunk *pcpu_reserved_chunk;
+#ifdef CONFIG_PERCPU_STATS
+
+#include <linux/spinlock.h>
+
+struct percpu_stats {
+ u64 nr_alloc; /* lifetime # of allocations */
+ u64 nr_dealloc; /* lifetime # of deallocations */
+ u64 nr_cur_alloc; /* current # of allocations */
+ u64 nr_max_alloc; /* max # of live allocations */
+ u32 nr_chunks; /* current # of live chunks */
+ u32 nr_max_chunks; /* max # of live chunks */
+ size_t min_alloc_size; /* min allocaiton size */
+ size_t max_alloc_size; /* max allocation size */
+};
+
+extern struct percpu_stats pcpu_stats;
+extern struct pcpu_alloc_info pcpu_stats_ai;
+
+/*
+ * For debug purposes. We don't care about the flexible array.
+ */
+static inline void pcpu_stats_save_ai(const struct pcpu_alloc_info *ai)
+{
+ memcpy(&pcpu_stats_ai, ai, sizeof(struct pcpu_alloc_info));
+
+ /* initialize min_alloc_size to unit_size */
+ pcpu_stats.min_alloc_size = pcpu_stats_ai.unit_size;
+}
+
+/*
+ * pcpu_stats_area_alloc - increment area allocation stats
+ * @chunk: the location of the area being allocated
+ * @size: size of area to allocate in bytes
+ *
+ * CONTEXT:
+ * pcpu_lock.
+ */
+static inline void pcpu_stats_area_alloc(struct pcpu_chunk *chunk, size_t size)
+{
+ lockdep_assert_held(&pcpu_lock);
+
+ pcpu_stats.nr_alloc++;
+ pcpu_stats.nr_cur_alloc++;
+ pcpu_stats.nr_max_alloc =
+ max(pcpu_stats.nr_max_alloc, pcpu_stats.nr_cur_alloc);
+ pcpu_stats.min_alloc_size =
+ min(pcpu_stats.min_alloc_size, size);
+ pcpu_stats.max_alloc_size =
+ max(pcpu_stats.max_alloc_size, size);
+
+ chunk->nr_alloc++;
+ chunk->max_alloc_size = max(chunk->max_alloc_size, size);
+}
+
+/*
+ * pcpu_stats_area_dealloc - decrement allocation stats
+ * @chunk: the location of the area being deallocated
+ *
+ * CONTEXT:
+ * pcpu_lock.
+ */
+static inline void pcpu_stats_area_dealloc(struct pcpu_chunk *chunk)
+{
+ lockdep_assert_held(&pcpu_lock);
+
+ pcpu_stats.nr_dealloc++;
+ pcpu_stats.nr_cur_alloc--;
+
+ chunk->nr_alloc--;
+}
+
+/*
+ * pcpu_stats_chunk_alloc - increment chunk stats
+ */
+static inline void pcpu_stats_chunk_alloc(void)
+{
+ spin_lock_irq(&pcpu_lock);
+
+ pcpu_stats.nr_chunks++;
+ pcpu_stats.nr_max_chunks =
+ max(pcpu_stats.nr_max_chunks, pcpu_stats.nr_chunks);
+
+ spin_unlock_irq(&pcpu_lock);
+}
+
+/*
+ * pcpu_stats_chunk_dealloc - decrement chunk stats
+ */
+static inline void pcpu_stats_chunk_dealloc(void)
+{
+ spin_lock_irq(&pcpu_lock);
+
+ pcpu_stats.nr_chunks--;
+
+ spin_unlock_irq(&pcpu_lock);
+}
+
+#else
+
+static inline void pcpu_stats_save_ai(const struct pcpu_alloc_info *ai)
+{
+}
+
+static inline void pcpu_stats_area_alloc(struct pcpu_chunk *chunk, size_t size)
+{
+}
+
+static inline void pcpu_stats_area_dealloc(struct pcpu_chunk *chunk)
+{
+}
+
+static inline void pcpu_stats_chunk_alloc(void)
+{
+}
+
+static inline void pcpu_stats_chunk_dealloc(void)
+{
+}
+
+#endif /* !CONFIG_PERCPU_STATS */
+
#endif
diff --git a/mm/percpu-km.c b/mm/percpu-km.c
index d66911ff42d9..3bbfa0c9d069 100644
--- a/mm/percpu-km.c
+++ b/mm/percpu-km.c
@@ -72,6 +72,8 @@ static struct pcpu_chunk *pcpu_create_chunk(void)
pcpu_chunk_populated(chunk, 0, nr_pages);
spin_unlock_irq(&pcpu_lock);
+ pcpu_stats_chunk_alloc();
+
return chunk;
}
@@ -79,6 +81,8 @@ static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
{
const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
+ pcpu_stats_chunk_dealloc();
+
if (chunk && chunk->data)
__free_pages(chunk->data, order_base_2(nr_pages));
pcpu_free_chunk(chunk);
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);
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index 9ac639499bd1..5915a224da52 100644
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -343,11 +343,16 @@ static struct pcpu_chunk *pcpu_create_chunk(void)
chunk->data = vms;
chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
+
+ pcpu_stats_chunk_alloc();
+
return chunk;
}
static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
{
+ pcpu_stats_chunk_dealloc();
+
if (chunk && chunk->data)
pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
pcpu_free_chunk(chunk);
diff --git a/mm/percpu.c b/mm/percpu.c
index 75ac982c19df..44a1cadf74a7 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -657,6 +657,7 @@ static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme,
int *p;
lockdep_assert_held(&pcpu_lock);
+ pcpu_stats_area_dealloc(chunk);
freeme |= 1; /* we are searching for <given offset, in use> pair */
@@ -721,6 +722,7 @@ static struct pcpu_chunk *pcpu_alloc_chunk(void)
chunk->map[0] = 0;
chunk->map[1] = pcpu_unit_size | 1;
chunk->map_used = 1;
+ chunk->has_reserved = false;
INIT_LIST_HEAD(&chunk->list);
INIT_LIST_HEAD(&chunk->map_extend_list);
@@ -970,6 +972,7 @@ restart:
goto restart;
area_found:
+ pcpu_stats_area_alloc(chunk, size);
spin_unlock_irqrestore(&pcpu_lock, flags);
/* populate if not all pages are already there */
@@ -1642,6 +1645,8 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
+ pcpu_stats_save_ai(ai);
+
/*
* Allocate chunk slots. The additional last slot is for
* empty chunks.
@@ -1685,6 +1690,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
if (schunk->free_size)
schunk->map[++schunk->map_used] = ai->static_size + schunk->free_size;
schunk->map[schunk->map_used] |= 1;
+ schunk->has_reserved = true;
/* init dynamic chunk if necessary */
if (dyn_size) {
@@ -1703,6 +1709,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
dchunk->map[1] = pcpu_reserved_chunk_limit;
dchunk->map[2] = (pcpu_reserved_chunk_limit + dchunk->free_size) | 1;
dchunk->map_used = 2;
+ dchunk->has_reserved = true;
}
/* link the first chunk in */
@@ -1711,6 +1718,8 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
pcpu_count_occupied_pages(pcpu_first_chunk, 1);
pcpu_chunk_relocate(pcpu_first_chunk, -1);
+ pcpu_stats_chunk_alloc();
+
/* we're done */
pcpu_base_addr = base_addr;
return 0;