[PATCH 2/2] mm/zsmalloc: add statistics support
From: Ganesh Mahendran
Date: Sat Dec 13 2014 - 08:45:34 EST
As a ram based memory allocator, keep the fragmentation in a low level
is our target. But now we still need to add the debug code in zsmalloc
to get the quantitative data.
After the RFC patch [1], Minchan Kim gave some suggestions.
[1] https://patchwork.kernel.org/patch/5469301/
This patch adds a new configuration CONFIG_ZSMALLOC_STAT to enable the statistics
collection for developers. Currently only the objects information in each class
are collected. User can get the information via debugfs. For example:
After I copy file 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 see the overall fragentation is:
(37022 - 36326) / 37022 = 1.87%
Also from the statistics we know why we got so low fragmentation:
Most of the objects is in class 254 with size 4096 Bytes. The pages in
zspage is 1. And there is only one object in a page. So, No fragmentation
will be produced.
Also we can collect other information and show it to user in the future.
Signed-off-by: Ganesh Mahendran <opensource.ganesh@xxxxxxxxx>
Suggested-by: Minchan Kim <minchan@xxxxxxxxxx>
---
mm/Kconfig | 10 ++++
mm/zsmalloc.c | 164 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 174 insertions(+)
diff --git a/mm/Kconfig b/mm/Kconfig
index 1d1ae6b..95c5728 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -601,6 +601,16 @@ config PGTABLE_MAPPING
You can check speed with zsmalloc benchmark:
https://github.com/spartacus06/zsmapbench
+config ZSMALLOC_STAT
+ bool "Export zsmalloc statistics"
+ depends on ZSMALLOC
+ select DEBUG_FS
+ help
+ This option enables code in the zsmalloc to collect various
+ statistics about whats happening in zsmalloc and exports that
+ information to userspace via debugfs.
+ If unsure, say N.
+
config GENERIC_EARLY_IOREMAP
bool
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index b724039..a8d0020 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -168,6 +168,8 @@ enum fullness_group {
ZS_FULL
};
+static int zs_pool_num;
+
/*
* number of size_classes
*/
@@ -200,6 +202,11 @@ struct size_class {
/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
int pages_per_zspage;
+#ifdef CONFIG_ZSMALLOC_STAT
+ unsigned long obj_allocated;
+ unsigned long obj_used;
+#endif
+
spinlock_t lock;
struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
@@ -221,6 +228,10 @@ struct zs_pool {
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 +953,132 @@ static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
return true;
}
+
+#ifdef CONFIG_ZSMALLOC_STAT
+#include <linux/debugfs.h>
+
+static struct dentry *zs_stat_root;
+
+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_show(struct seq_file *s, void *v)
+{
+ int i;
+ struct zs_pool *pool = (struct zs_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 = class->obj_allocated;
+ obj_used = class->obj_used;
+ objs_per_zspage = get_maxobj_per_zspage(class->size,
+ class->pages_per_zspage);
+ pages_used = obj_allocated / objs_per_zspage *
+ class->pages_per_zspage;
+
+ spin_unlock(&class->lock);
+
+ seq_printf(s, " %5u %5u %10lu %10lu %10lu\n", i, class->size,
+ obj_allocated, obj_used, pages_used);
+
+ total_objs += class->obj_allocated;
+ total_used_objs += class->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_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, zs_stats_show, inode->i_private);
+}
+
+static const struct file_operations zs_stats_operations = {
+ .open = zs_stats_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int zs_pool_stat_create(struct zs_pool *pool, int index)
+{
+ char name[10];
+ int ret = 0;
+
+ if (!zs_stat_root) {
+ ret = -ENODEV;
+ goto out;
+ }
+
+ snprintf(name, sizeof(name), "pool-%d", index);
+ pool->stat_dentry = debugfs_create_dir(name, zs_stat_root);
+ if (!pool->stat_dentry) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ debugfs_create_file("obj_in_classes", S_IFREG | S_IRUGO,
+ pool->stat_dentry, pool, &zs_stats_operations);
+
+out:
+ return ret;
+}
+
+static void zs_pool_stat_destroy(struct zs_pool *pool)
+{
+ debugfs_remove_recursive(pool->stat_dentry);
+}
+
+#else /* CONFIG_ZSMALLOC_STAT */
+
+static int __init zs_stat_init(void)
+{
+ return 0;
+}
+
+static void __exit zs_stat_exit(void) { }
+
+static inline int zs_pool_stat_create(struct zs_pool *pool, int index)
+{
+ 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);
@@ -1075,6 +1212,10 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size)
atomic_long_add(class->pages_per_zspage,
&pool->pages_allocated);
spin_lock(&class->lock);
+#ifdef CONFIG_ZSMALLOC_STAT
+ class->obj_allocated += get_maxobj_per_zspage(class->size,
+ class->pages_per_zspage);
+#endif
}
obj = (unsigned long)first_page->freelist;
@@ -1088,6 +1229,9 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size)
kunmap_atomic(vaddr);
first_page->inuse++;
+#ifdef CONFIG_ZSMALLOC_STAT
+ class->obj_used++;
+#endif
/* Now move the zspage to another fullness group, if required */
fix_fullness_group(pool, first_page);
spin_unlock(&class->lock);
@@ -1127,12 +1271,19 @@ void zs_free(struct zs_pool *pool, unsigned long obj)
first_page->freelist = (void *)obj;
first_page->inuse--;
+#ifdef CONFIG_ZSMALLOC_STAT
+ class->obj_used--;
+#endif
fullness = fix_fullness_group(pool, first_page);
spin_unlock(&class->lock);
if (fullness == ZS_EMPTY) {
atomic_long_sub(class->pages_per_zspage,
&pool->pages_allocated);
+#ifdef CONFIG_ZSMALLOC_STAT
+ class->obj_allocated -= get_maxobj_per_zspage(class->size,
+ class->pages_per_zspage);
+#endif
free_zspage(first_page);
}
}
@@ -1209,6 +1360,10 @@ struct zs_pool *zs_create_pool(gfp_t flags)
}
pool->flags = flags;
+ zs_pool_num++;
+
+ if (zs_pool_stat_create(pool, zs_pool_num))
+ pr_warn("zs pool %d stat initialization failed\n", zs_pool_num);
return pool;
@@ -1241,6 +1396,9 @@ void zs_destroy_pool(struct zs_pool *pool)
kfree(class);
}
+ zs_pool_stat_destroy(pool);
+ zs_pool_num--;
+
kfree(pool->size_class);
kfree(pool);
}
@@ -1260,6 +1418,10 @@ static int __init zs_init(void)
#ifdef CONFIG_ZPOOL
zpool_register_driver(&zs_zpool_driver);
#endif
+
+ if (zs_stat_init())
+ pr_warn("zs stat initialization failed\n");
+
return 0;
}
@@ -1269,6 +1431,8 @@ static void __exit zs_exit(void)
zpool_unregister_driver(&zs_zpool_driver);
#endif
zs_unregister_cpu_notifier();
+
+ zs_stat_exit();
}
module_init(zs_init);
--
1.7.9.5
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