[PATCHv3 4/8] zram: use atomic64_t for all zram stats

Sergey Senozhatsky
2014-01-16T13:16:05Z

This is a preparation patch for stats code duplication removal.

1) use atomic64_t for `pages_zero' and `pages_stored' zram stats.
2) `compr_size' and `pages_zero' struct zram_stats members did not
follow the existing device attr naming scheme: zram_stats.ATTR has
ATTR_show() function. rename them:
-- compr_size -> compr_data_size
-- pages_zero -> zero_pages

Minchan Kim's note:
If we really have trouble with atomic stat operation, we could
change it with percpu_counter so that it could solve atomic overhead and
unnecessary memory space by introducing unsigned long instead of 64bit
atomic_t.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
drivers/block/zram/zram_drv.c | 18 +++++++++---------
drivers/block/zram/zram_drv.h | 6 +++---
2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index c7c7789..0035d39 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -109,7 +109,7 @@ static ssize_t zero_pages_show(struct device *dev,
{
struct zram *zram = dev_to_zram(dev);

- return sprintf(buf, "%u\n", atomic_read(&zram->stats.pages_zero));
+ return sprintf(buf, "%llu\n", (u64)atomic64_read(&zram->stats.zero_pages));
}

static ssize_t orig_data_size_show(struct device *dev,
@@ -118,7 +118,7 @@ static ssize_t orig_data_size_show(struct device *dev,
struct zram *zram = dev_to_zram(dev);

return sprintf(buf, "%llu\n",
- (u64)(atomic_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
+ (u64)(atomic64_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
}

static ssize_t compr_data_size_show(struct device *dev,
@@ -127,7 +127,7 @@ static ssize_t compr_data_size_show(struct device *dev,
struct zram *zram = dev_to_zram(dev);

return sprintf(buf, "%llu\n",
- (u64)atomic64_read(&zram->stats.compr_size));
+ (u64)atomic64_read(&zram->stats.compr_data_size));
}

static ssize_t mem_used_total_show(struct device *dev,
@@ -301,15 +301,15 @@ static void zram_free_page(struct zram *zram, size_t index)
*/
if (zram_test_flag(meta, index, ZRAM_ZERO)) {
zram_clear_flag(meta, index, ZRAM_ZERO);
- atomic_dec(&zram->stats.pages_zero);
+ atomic64_dec(&zram->stats.zero_pages);
}
return;
}

zs_free(meta->mem_pool, handle);

- atomic64_sub(meta->table[index].size, &zram->stats.compr_size);
- atomic_dec(&zram->stats.pages_stored);
+ atomic64_sub(meta->table[index].size, &zram->stats.compr_data_size);
+ atomic64_dec(&zram->stats.pages_stored);

meta->table[index].handle = 0;
meta->table[index].size = 0;
@@ -452,7 +452,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
zram_set_flag(meta, index, ZRAM_ZERO);
write_unlock(&zram->meta->tb_lock);

- atomic_inc(&zram->stats.pages_zero);
+ atomic64_inc(&zram->stats.zero_pages);
ret = 0;
goto out;
}
@@ -508,8 +508,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
write_unlock(&zram->meta->tb_lock);

/* Update stats */
- atomic64_add(clen, &zram->stats.compr_size);
- atomic_inc(&zram->stats.pages_stored);
+ atomic64_add(clen, &zram->stats.compr_data_size);
+ atomic64_inc(&zram->stats.pages_stored);
out:
if (locked)
mutex_unlock(&meta->buffer_lock);
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 2f173cb..58d4ac5 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -69,15 +69,15 @@ struct table {
} __aligned(4);

struct zram_stats {
- atomic64_t compr_size; /* compressed size of pages stored */
+ atomic64_t compr_data_size; /* compressed size of pages stored */
atomic64_t num_reads; /* failed + successful */
atomic64_t num_writes; /* --do-- */
atomic64_t failed_reads; /* should NEVER! happen */
atomic64_t failed_writes; /* can happen when memory is too low */
atomic64_t invalid_io; /* non-page-aligned I/O requests */
atomic64_t notify_free; /* no. of swap slot free notifications */
- atomic_t pages_zero; /* no. of zero filled pages */
- atomic_t pages_stored; /* no. of pages currently stored */
+ atomic64_t zero_pages; /* no. of zero filled pages */
+ atomic64_t pages_stored; /* no. of pages currently stored */
};

struct zram_meta {
--
1.8.5.3.493.gb139ac2