mm/zsmalloc: add statistics support
Keeping fragmentation of zsmalloc in a low level is our target. But now
we still need to add the debug code in zsmalloc to get the quantitative
data.
This patch adds a new configuration CONFIG_ZSMALLOC_STAT to enable the
statistics collection for developers. Currently only the objects
statatitics in each class are collected. User can get the information via
debugfs.
cat /sys/kernel/debug/zsmalloc/zram0/...
For example:
After I copied "jdk-8u25-linux-x64.tar.gz" to zram with ext4 filesystem:
class size obj_allocated obj_used pages_used
0 32 0 0 0
1 48 256 12 3
2 64 64 14 1
3 80 51 7 1
4 96 128 5 3
5 112 73 5 2
6 128 32 4 1
7 144 0 0 0
8 160 0 0 0
9 176 0 0 0
10 192 0 0 0
11 208 0 0 0
12 224 0 0 0
13 240 0 0 0
14 256 16 1 1
15 272 15 9 1
16 288 0 0 0
17 304 0 0 0
18 320 0 0 0
19 336 0 0 0
20 352 0 0 0
21 368 0 0 0
22 384 0 0 0
23 400 0 0 0
24 416 0 0 0
25 432 0 0 0
26 448 0 0 0
27 464 0 0 0
28 480 0 0 0
29 496 33 1 4
30 512 0 0 0
31 528 0 0 0
32 544 0 0 0
33 560 0 0 0
34 576 0 0 0
35 592 0 0 0
36 608 0 0 0
37 624 0 0 0
38 640 0 0 0
40 672 0 0 0
42 704 0 0 0
43 720 17 1 3
44 736 0 0 0
46 768 0 0 0
49 816 0 0 0
51 848 0 0 0
52 864 14 1 3
54 896 0 0 0
57 944 13 1 3
58 960 0 0 0
62 1024 4 1 1
66 1088 15 2 4
67 1104 0 0 0
71 1168 0 0 0
74 1216 0 0 0
76 1248 0 0 0
83 1360 3 1 1
91 1488 11 1 4
94 1536 0 0 0
100 1632 5 1 2
107 1744 0 0 0
111 1808 9 1 4
126 2048 4 4 2
144 2336 7 3 4
151 2448 0 0 0
168 2720 15 15 10
190 3072 28 27 21
202 3264 0 0 0
254 4096 36209 36209 36209
Total 37022 36326 36288
We can calculate the overall fragentation by the last line:
Total 37022 36326 36288
(37022 - 36326) / 37022 = 1.87%
Also by analysing objects alocated in every class we know why we got so
low fragmentation: Most of the allocated objects is in <class 254>. And
there is only 1 page in class 254 zspage. So, No fragmentation will be
introduced by allocating objs in class 254.
And in future, we can collect other zsmalloc statistics as we need and
analyse them.
Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Suggested-by: Minchan Kim <minchan@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 2359e61..0dec1fa 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -91,6 +91,7 @@
#include <linux/hardirq.h>
#include <linux/spinlock.h>
#include <linux/types.h>
+#include <linux/debugfs.h>
#include <linux/zsmalloc.h>
#include <linux/zpool.h>
@@ -168,6 +169,22 @@
ZS_FULL
};
+enum zs_stat_type {
+ OBJ_ALLOCATED,
+ OBJ_USED,
+ NR_ZS_STAT_TYPE,
+};
+
+#ifdef CONFIG_ZSMALLOC_STAT
+
+static struct dentry *zs_stat_root;
+
+struct zs_size_stat {
+ unsigned long objs[NR_ZS_STAT_TYPE];
+};
+
+#endif
+
/*
* number of size_classes
*/
@@ -200,6 +217,10 @@
/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
int pages_per_zspage;
+#ifdef CONFIG_ZSMALLOC_STAT
+ struct zs_size_stat stats;
+#endif
+
spinlock_t lock;
struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
@@ -217,10 +238,16 @@
};
struct zs_pool {
+ char *name;
+
struct size_class **size_class;
gfp_t flags; /* allocation flags used when growing pool */
atomic_long_t pages_allocated;
+
+#ifdef CONFIG_ZSMALLOC_STAT
+ struct dentry *stat_dentry;
+#endif
};
/*
@@ -942,6 +969,166 @@
return true;
}
+#ifdef CONFIG_ZSMALLOC_STAT
+
+static inline void zs_stat_inc(struct size_class *class,
+ enum zs_stat_type type, unsigned long cnt)
+{
+ class->stats.objs[type] += cnt;
+}
+
+static inline void zs_stat_dec(struct size_class *class,
+ enum zs_stat_type type, unsigned long cnt)
+{
+ class->stats.objs[type] -= cnt;
+}
+
+static inline unsigned long zs_stat_get(struct size_class *class,
+ enum zs_stat_type type)
+{
+ return class->stats.objs[type];
+}
+
+static int __init zs_stat_init(void)
+{
+ if (!debugfs_initialized())
+ return -ENODEV;
+
+ zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
+ if (!zs_stat_root)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void __exit zs_stat_exit(void)
+{
+ debugfs_remove_recursive(zs_stat_root);
+}
+
+static int zs_stats_size_show(struct seq_file *s, void *v)
+{
+ int i;
+ struct zs_pool *pool = s->private;
+ struct size_class *class;
+ int objs_per_zspage;
+ unsigned long obj_allocated, obj_used, pages_used;
+ unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
+
+ seq_printf(s, " %5s %5s %13s %10s %10s\n", "class", "size",
+ "obj_allocated", "obj_used", "pages_used");
+
+ for (i = 0; i < zs_size_classes; i++) {
+ class = pool->size_class[i];
+
+ if (class->index != i)
+ continue;
+
+ spin_lock(&class->lock);
+ obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
+ obj_used = zs_stat_get(class, OBJ_USED);
+ spin_unlock(&class->lock);
+
+ objs_per_zspage = get_maxobj_per_zspage(class->size,
+ class->pages_per_zspage);
+ pages_used = obj_allocated / objs_per_zspage *
+ class->pages_per_zspage;
+
+ seq_printf(s, " %5u %5u %10lu %10lu %10lu\n", i,
+ class->size, obj_allocated, obj_used, pages_used);
+
+ total_objs += obj_allocated;
+ total_used_objs += obj_used;
+ total_pages += pages_used;
+ }
+
+ seq_puts(s, "\n");
+ seq_printf(s, " %5s %5s %10lu %10lu %10lu\n", "Total", "",
+ total_objs, total_used_objs, total_pages);
+
+ return 0;
+}
+
+static int zs_stats_size_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, zs_stats_size_show, inode->i_private);
+}
+
+static const struct file_operations zs_stat_size_ops = {
+ .open = zs_stats_size_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int zs_pool_stat_create(char *name, struct zs_pool *pool)
+{
+ struct dentry *entry;
+
+ if (!zs_stat_root)
+ return -ENODEV;
+
+ entry = debugfs_create_dir(name, zs_stat_root);
+ if (!entry) {
+ pr_warn("debugfs dir <%s> creation failed\n", name);
+ return -ENOMEM;
+ }
+ pool->stat_dentry = entry;
+
+ entry = debugfs_create_file("obj_in_classes", S_IFREG | S_IRUGO,
+ pool->stat_dentry, pool, &zs_stat_size_ops);
+ if (!entry) {
+ pr_warn("%s: debugfs file entry <%s> creation failed\n",
+ name, "obj_in_classes");
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void zs_pool_stat_destroy(struct zs_pool *pool)
+{
+ debugfs_remove_recursive(pool->stat_dentry);
+}
+
+#else /* CONFIG_ZSMALLOC_STAT */
+
+static inline void zs_stat_inc(struct size_class *class,
+ enum zs_stat_type type, unsigned long cnt)
+{
+}
+
+static inline void zs_stat_dec(struct size_class *class,
+ enum zs_stat_type type, unsigned long cnt)
+{
+}
+
+static inline unsigned long zs_stat_get(struct size_class *class,
+ enum zs_stat_type type)
+{
+ return 0;
+}
+
+static int __init zs_stat_init(void)
+{
+ return 0;
+}
+
+static void __exit zs_stat_exit(void)
+{
+}
+
+static inline int zs_pool_stat_create(char *name, struct zs_pool *pool)
+{
+ return 0;
+}
+
+static inline void zs_pool_stat_destroy(struct zs_pool *pool)
+{
+}
+
+#endif
+
unsigned long zs_get_total_pages(struct zs_pool *pool)
{
return atomic_long_read(&pool->pages_allocated);
@@ -1074,7 +1261,10 @@
set_zspage_mapping(first_page, class->index, ZS_EMPTY);
atomic_long_add(class->pages_per_zspage,
&pool->pages_allocated);
+
spin_lock(&class->lock);
+ zs_stat_inc(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
+ class->size, class->pages_per_zspage));
}
obj = (unsigned long)first_page->freelist;
@@ -1088,6 +1278,7 @@
kunmap_atomic(vaddr);
first_page->inuse++;
+ zs_stat_inc(class, OBJ_USED, 1);
/* Now move the zspage to another fullness group, if required */
fix_fullness_group(pool, first_page);
spin_unlock(&class->lock);
@@ -1128,6 +1319,12 @@
first_page->inuse--;
fullness = fix_fullness_group(pool, first_page);
+
+ zs_stat_dec(class, OBJ_USED, 1);
+ if (fullness == ZS_EMPTY)
+ zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
+ class->size, class->pages_per_zspage));
+
spin_unlock(&class->lock);
if (fullness == ZS_EMPTY) {
@@ -1158,9 +1355,16 @@
if (!pool)
return NULL;
+ pool->name = kstrdup(name, GFP_KERNEL);
+ if (!pool->name) {
+ kfree(pool);
+ return NULL;
+ }
+
pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *),
GFP_KERNEL);
if (!pool->size_class) {
+ kfree(pool->name);
kfree(pool);
return NULL;
}
@@ -1210,6 +1414,9 @@
pool->flags = flags;
+ if (zs_pool_stat_create(name, pool))
+ goto err;
+
return pool;
err:
@@ -1222,6 +1429,8 @@
{
int i;
+ zs_pool_stat_destroy(pool);
+
for (i = 0; i < zs_size_classes; i++) {
int fg;
struct size_class *class = pool->size_class[i];
@@ -1242,6 +1451,7 @@
}
kfree(pool->size_class);
+ kfree(pool->name);
kfree(pool);
}
EXPORT_SYMBOL_GPL(zs_destroy_pool);
@@ -1250,17 +1460,30 @@
{
int ret = zs_register_cpu_notifier();
- if (ret) {
- zs_unregister_cpu_notifier();
- return ret;
- }
+ if (ret)
+ goto notifier_fail;
init_zs_size_classes();
#ifdef CONFIG_ZPOOL
zpool_register_driver(&zs_zpool_driver);
#endif
+
+ ret = zs_stat_init();
+ if (ret) {
+ pr_err("zs stat initialization failed\n");
+ goto stat_fail;
+ }
return 0;
+
+stat_fail:
+#ifdef CONFIG_ZPOOL
+ zpool_unregister_driver(&zs_zpool_driver);
+#endif
+notifier_fail:
+ zs_unregister_cpu_notifier();
+
+ return ret;
}
static void __exit zs_exit(void)
@@ -1269,6 +1492,8 @@
zpool_unregister_driver(&zs_zpool_driver);
#endif
zs_unregister_cpu_notifier();
+
+ zs_stat_exit();
}
module_init(zs_init);