From: Joonsoo Kim <iamjoonsoo....@lge.com>
Benefit of deduplication is dependent on the workload so it's not
preferable to always enable. Therefore, make it optional.
Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com>
---
drivers/block/zram/zram_drv.c | 80 ++++++++++++++++++++++++++++++++++++++-----
drivers/block/zram/zram_drv.h | 1 +
2 files changed, 73 insertions(+), 8 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 012425f..e45aa9f 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -328,6 +328,39 @@ static ssize_t comp_algorithm_store(struct device *dev,
return len;
}
+static ssize_t use_dedup_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int val;
+ struct zram *zram = dev_to_zram(dev);
+
+ down_read(&zram->init_lock);
+ val = zram->use_dedup;
+ up_read(&zram->init_lock);
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+static ssize_t use_dedup_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ int val;
+ struct zram *zram = dev_to_zram(dev);
+
+ if (kstrtoint(buf, 10, &val) || (val != 0 && val != 1))
+ return -EINVAL;
+
+ down_write(&zram->init_lock);
+ if (init_done(zram)) {
+ up_write(&zram->init_lock);
+ pr_info("Can't change dedup usage for initialized device\n");
+ return -EBUSY;
+ }
+ zram->use_dedup = val;
+ up_write(&zram->init_lock);
+ return len;
+}
+
static ssize_t compact_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
{
@@ -422,11 +455,23 @@ static ssize_t debug_stat_show(struct device *dev,
static DEVICE_ATTR_RO(mm_stat);
static DEVICE_ATTR_RO(debug_stat);
-static u32 zram_calc_checksum(unsigned char *mem)
+static u32 zram_calc_checksum(struct zram *zram, unsigned char *mem)
{
+ if (!zram->use_dedup)
+ return 0;
+
return jhash(mem, PAGE_SIZE, 0);
}
+static unsigned long zram_entry_handle(struct zram *zram,
+ struct zram_entry *entry)
+{
+ if (!zram->use_dedup)
+ return (unsigned long)entry;
+
+ return entry->handle;
+}
+
static struct zram_entry *zram_entry_alloc(struct zram *zram,
unsigned int len, gfp_t flags)
{
@@ -438,6 +483,9 @@ static struct zram_entry *zram_entry_alloc(struct zram
*zram,
if (!handle)
return NULL;
+ if (!zram->use_dedup)
+ return (struct zram_entry *)handle;
+
entry = kzalloc(sizeof(*entry), flags);
if (!entry) {
zs_free(meta->mem_pool, handle);
@@ -462,6 +510,9 @@ static void zram_entry_insert(struct zram *zram, struct
zram_entry *new,
struct rb_node **rb_node, *parent = NULL;
struct zram_entry *entry;
+ if (!zram->use_dedup)
+ return;
+
new->checksum = checksum;
hash = &meta->hash[checksum % meta->hash_size];
rb_root = &hash->rb_root;
@@ -492,7 +543,8 @@ static bool zram_entry_match(struct zram *zram, struct
zram_entry *entry,
struct zram_meta *meta = zram->meta;
struct zcomp_strm *zstrm;
- cmem = zs_map_object(meta->mem_pool, entry->handle, ZS_MM_RO);
+ cmem = zs_map_object(meta->mem_pool,
+ zram_entry_handle(zram, entry), ZS_MM_RO);
if (entry->len == PAGE_SIZE) {
match = !memcmp(mem, cmem, PAGE_SIZE);
} else {
@@ -501,7 +553,7 @@ static bool zram_entry_match(struct zram *zram, struct
zram_entry *entry,
match = !memcmp(mem, zstrm->buffer, PAGE_SIZE);
zcomp_stream_put(zram->comp);
}
- zs_unmap_object(meta->mem_pool, entry->handle);
+ zs_unmap_object(meta->mem_pool, zram_entry_handle(zram, entry));
return match;
}
@@ -521,6 +573,11 @@ static bool zram_entry_put(struct zram *zram, struct
zram_meta *meta,
struct zram_hash *hash;
u32 checksum;
+ if (!zram->use_dedup) {
+ zs_free(meta->mem_pool, zram_entry_handle(zram, entry));
+ return false;
+ }
+
if (!populated)
goto free;
@@ -551,6 +608,9 @@ static struct zram_entry *zram_entry_get(struct zram *zram,
struct zram_entry *entry;
struct rb_node *rb_node;
+ if (!zram->use_dedup)
+ return NULL;
+
hash = &meta->hash[checksum % meta->hash_size];
spin_lock(&hash->lock);
@@ -713,7 +773,8 @@ static int zram_decompress_page(struct zram *zram, char
*mem, u32 index)
return 0;
}
- cmem = zs_map_object(meta->mem_pool, entry->handle, ZS_MM_RO);
+ cmem = zs_map_object(meta->mem_pool,
+ zram_entry_handle(zram, entry), ZS_MM_RO);
if (size == PAGE_SIZE) {
copy_page(mem, cmem);
} else {
@@ -722,7 +783,7 @@ static int zram_decompress_page(struct zram *zram, char
*mem, u32 index)
ret = zcomp_decompress(zstrm, cmem, size, mem);
zcomp_stream_put(zram->comp);
}
- zs_unmap_object(meta->mem_pool, entry->handle);
+ zs_unmap_object(meta->mem_pool, zram_entry_handle(zram, entry));
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
/* Should NEVER happen. Return bio error if it does. */
@@ -840,7 +901,7 @@ static int zram_bvec_write(struct zram *zram, struct
bio_vec *bvec, u32 index,
goto out;
}
- checksum = zram_calc_checksum(uncmem);
+ checksum = zram_calc_checksum(zram, uncmem);
if (!entry) {
entry = zram_entry_get(zram, uncmem, checksum);
if (entry) {
@@ -915,7 +976,8 @@ static int zram_bvec_write(struct zram *zram, struct
bio_vec *bvec, u32 index,
goto out;
}
- cmem = zs_map_object(meta->mem_pool, entry->handle, ZS_MM_WO);
+ cmem = zs_map_object(meta->mem_pool,
+ zram_entry_handle(zram, entry), ZS_MM_WO);
if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
src = kmap_atomic(page);
@@ -927,7 +989,7 @@ static int zram_bvec_write(struct zram *zram, struct
bio_vec *bvec, u32 index,
zcomp_stream_put(zram->comp);
zstrm = NULL;
- zs_unmap_object(meta->mem_pool, entry->handle);
+ zs_unmap_object(meta->mem_pool, zram_entry_handle(zram, entry));
zram_entry_insert(zram, entry, checksum);
found_duplication:
@@ -1310,6 +1372,7 @@ static int zram_open(struct block_device *bdev, fmode_t
mode)
static DEVICE_ATTR_WO(mem_used_max);
static DEVICE_ATTR_RW(max_comp_streams);
static DEVICE_ATTR_RW(comp_algorithm);
+static DEVICE_ATTR_RW(use_dedup);
static struct attribute *zram_disk_attrs[] = {
&dev_attr_disksize.attr,
@@ -1320,6 +1383,7 @@ static int zram_open(struct block_device *bdev, fmode_t
mode)
&dev_attr_mem_used_max.attr,
&dev_attr_max_comp_streams.attr,
&dev_attr_comp_algorithm.attr,
+ &dev_attr_use_dedup.attr,
&dev_attr_io_stat.attr,
&dev_attr_mm_stat.attr,
&dev_attr_debug_stat.attr,
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 07d1f8d..b823555 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -141,5 +141,6 @@ struct zram {
* zram is claimed so open request will be failed
*/
bool claim; /* Protected by bdev->bd_mutex */
+ int use_dedup;
};
#endif
--
1.9.1
