[RFC][PATCHv3 6/7] zsmalloc/zram: move `num_migrated' to zs_pool

Sergey Senozhatsky
2015-06-18T11:48:19Z

Remove the number of migrated objects from `zs_compact_control'
and move it to `zs_pool'. `zs_compact_control' has a limited
lifespan, we lose it when zs_compaction() returns back to zram.

To keep track of objects migrated during auto-compaction (issued
by the shrinker) we need to store this number in zs_pool.

Introduce zs_get_num_migrated() to export zs_pool's ->num_migrated
counter and use it in zram, so we can also drop a zram's copy of
`num_migrated'.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
drivers/block/zram/zram_drv.c | 12 ++++++------
drivers/block/zram/zram_drv.h | 1 -
include/linux/zsmalloc.h | 1 +
mm/zsmalloc.c | 41 +++++++++++++++++++----------------------
4 files changed, 26 insertions(+), 29 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index fb655e8..28ad3f8 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -388,7 +388,6 @@ static ssize_t comp_algorithm_store(struct device *dev,
static ssize_t compact_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
{
- unsigned long nr_migrated;
struct zram *zram = dev_to_zram(dev);
struct zram_meta *meta;

@@ -399,8 +398,7 @@ static ssize_t compact_store(struct device *dev,
}

meta = zram->meta;
- nr_migrated = zs_compact(meta->mem_pool);
- atomic64_add(nr_migrated, &zram->stats.num_migrated);
+ zs_compact(meta->mem_pool);
up_read(&zram->init_lock);

return len;
@@ -428,13 +426,15 @@ static ssize_t mm_stat_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
- u64 orig_size, mem_used = 0;
+ u64 orig_size, mem_used = 0, num_migrated = 0;
long max_used;
ssize_t ret;

down_read(&zram->init_lock);
- if (init_done(zram))
+ if (init_done(zram)) {
mem_used = zs_get_total_pages(zram->meta->mem_pool);
+ num_migrated = zs_get_num_migrated(zram->meta->mem_pool);
+ }

orig_size = atomic64_read(&zram->stats.pages_stored);
max_used = atomic_long_read(&zram->stats.max_used_pages);
@@ -447,7 +447,7 @@ static ssize_t mm_stat_show(struct device *dev,
zram->limit_pages << PAGE_SHIFT,
max_used << PAGE_SHIFT,
(u64)atomic64_read(&zram->stats.zero_pages),
- (u64)atomic64_read(&zram->stats.num_migrated));
+ num_migrated);
up_read(&zram->init_lock);

return ret;
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 6dbe2df..8e92339 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -78,7 +78,6 @@ struct zram_stats {
atomic64_t compr_data_size; /* compressed size of pages stored */
atomic64_t num_reads; /* failed + successful */
atomic64_t num_writes; /* --do-- */
- atomic64_t num_migrated; /* no. of migrated object */
atomic64_t failed_reads; /* can happen when memory is too low */
atomic64_t failed_writes; /* can happen when memory is too low */
atomic64_t invalid_io; /* non-page-aligned I/O requests */
diff --git a/include/linux/zsmalloc.h b/include/linux/zsmalloc.h
index 1338190..e878875 100644
--- a/include/linux/zsmalloc.h
+++ b/include/linux/zsmalloc.h
@@ -47,6 +47,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
void zs_unmap_object(struct zs_pool *pool, unsigned long handle);

unsigned long zs_get_total_pages(struct zs_pool *pool);
+unsigned long zs_get_num_migrated(struct zs_pool *pool);
unsigned long zs_compact(struct zs_pool *pool);

#endif
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 5fa96ae..c9aea0a 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -237,16 +237,19 @@ struct link_free {
};

struct zs_pool {
- char *name;
+ char *name;

- struct size_class **size_class;
- struct kmem_cache *handle_cachep;
+ struct size_class **size_class;
+ struct kmem_cache *handle_cachep;

- gfp_t flags; /* allocation flags used when growing pool */
- atomic_long_t pages_allocated;
+ /* Allocation flags used when growing pool */
+ gfp_t flags;
+ atomic_long_t pages_allocated;
+ /* How many objects were migrated */
+ unsigned long num_migrated;

#ifdef CONFIG_ZSMALLOC_STAT
- struct dentry *stat_dentry;
+ struct dentry *stat_dentry;
#endif
};

@@ -1220,6 +1223,12 @@ unsigned long zs_get_total_pages(struct zs_pool *pool)
}
EXPORT_SYMBOL_GPL(zs_get_total_pages);

+unsigned long zs_get_num_migrated(struct zs_pool *pool)
+{
+ return pool->num_migrated;
+}
+EXPORT_SYMBOL_GPL(zs_get_num_migrated);
+
/**
* zs_map_object - get address of allocated object from handle.
* @pool: pool from which the object was allocated
@@ -1586,8 +1595,6 @@ struct zs_compact_control {
/* Starting object index within @s_page which used for live object
* in the subpage. */
int index;
- /* how many of objects are migrated */
- int nr_migrated;
};

static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
@@ -1598,7 +1605,6 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
struct page *s_page = cc->s_page;
struct page *d_page = cc->d_page;
unsigned long index = cc->index;
- int nr_migrated = 0;
int ret = 0;

while (1) {
@@ -1625,13 +1631,12 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
record_obj(handle, free_obj);
unpin_tag(handle);
obj_free(pool, class, used_obj);
- nr_migrated++;
+ pool->num_migrated++;
}

/* Remember last position in this iteration */
cc->s_page = s_page;
cc->index = index;
- cc->nr_migrated = nr_migrated;

return ret;
}
@@ -1706,13 +1711,11 @@ static unsigned long zs_can_compact(struct size_class *class)
return obj_wasted;
}

-static unsigned long __zs_compact(struct zs_pool *pool,
- struct size_class *class)
+static void __zs_compact(struct zs_pool *pool, struct size_class *class)
{
struct zs_compact_control cc;
struct page *src_page;
struct page *dst_page = NULL;
- unsigned long nr_total_migrated = 0;

spin_lock(&class->lock);
while ((src_page = isolate_source_page(class))) {
@@ -1735,7 +1738,6 @@ static unsigned long __zs_compact(struct zs_pool *pool,
break;

putback_zspage(pool, class, dst_page);
- nr_total_migrated += cc.nr_migrated;
}

/* Stop if we couldn't find slot */
@@ -1745,7 +1747,6 @@ static unsigned long __zs_compact(struct zs_pool *pool,
putback_zspage(pool, class, dst_page);
putback_zspage(pool, class, src_page);
spin_unlock(&class->lock);
- nr_total_migrated += cc.nr_migrated;
cond_resched();
spin_lock(&class->lock);
}
@@ -1754,14 +1755,11 @@ static unsigned long __zs_compact(struct zs_pool *pool,
putback_zspage(pool, class, src_page);

spin_unlock(&class->lock);
-
- return nr_total_migrated;
}

unsigned long zs_compact(struct zs_pool *pool)
{
int i;
- unsigned long nr_migrated = 0;
struct size_class *class;

for (i = zs_size_classes - 1; i >= 0; i--) {
@@ -1770,10 +1768,9 @@ unsigned long zs_compact(struct zs_pool *pool)
continue;
if (class->index != i)
continue;
- nr_migrated += __zs_compact(pool, class);
+ __zs_compact(pool, class);
}
-
- return nr_migrated;
+ return pool->num_migrated;
}
EXPORT_SYMBOL_GPL(zs_compact);

--
2.4.4