On Sat, Dec 13, 2014 at 09:45:14PM +0800, Ganesh Mahendran wrote: > As a ram based memory allocator, keep the fragmentation in a low level Just say, zsmalloc. > 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. So, could you make zs > > 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; What's this? What protects the race? It means description. > + > /* > * 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 I perfer creating new struct. struct zs_size_stat { unsigend long obj_allocated; unsignged long obj_used; }; > + > 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> A question: Why "#include" is here instead of top on the source file? > + > +static struct dentry *zs_stat_root; > + > +static int __init zs_stat_init(void) > +{ > + if (!debugfs_initialized()) > + return -ENODEV; Do we need above check? When I read comment of debugfs_create_dir, it says "If debugfs is not enabled in the kernel, the value -%ENODEV will be returned." > + > + zs_stat_root = debugfs_create_dir("zsmalloc", NULL); > + if (!zs_stat_root) > + return -ENOMEM; On null return of debugfs_create_dir, it means always 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; I think We don't need to protect class->pages_per_zspage with class->lock. > + > + 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; You couldn't access class->fields without class lock. Please, assign them into local variable under the lock and sum them without the lock. > + 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); Hmm, how does admin know any zsmalloc instance is associated with any block device? Maybe we need export zspool index to the client and print it when pool is populated. > + 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); No need to check return? > + > +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 I prefer zs_stat_inc(class, OBJ_ALLOCATED, get_max_obj()); > } > > 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 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); > @@ -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 zs_stat_dec(class, OBJ_USED, 1) > 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 zs_stat_dec(class, OBJ_ALLOCATED, get_max_obj()); > free_zspage(first_page); > } > } > @@ -1209,6 +1360,10 @@ struct zs_pool *zs_create_pool(gfp_t flags) > } > > pool->flags = flags; > + zs_pool_num++; Who protect the race? And manybe we should keep the index in zspool and export it to the user to let them know what zsmalloc instance is thiers. > + > + 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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