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.gan...@gmail.com> Suggested-by: Minchan Kim <minc...@kernel.org> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
