[PATCHv2 0/4] zram stats rework and code cleanup

[PATCHv2 0/4] zram stats rework and code cleanup

[Sergey Senozhatsky]

This patchset includes zram stats clean up and enhancements.

Sergey Senozhatsky (4):
  zram: drop `init_done' struct zram member
  zram: do not pass rw argument to __zram_make_request()
  zram: rework reported to end-user zram statistics
  zram: report failed read and writes stats

 drivers/block/zram/zram_drv.c | 210 ++++++++++++++----------------------------
 drivers/block/zram/zram_drv.h |  18 ++--
 2 files changed, 74 insertions(+), 154 deletions(-)

-- 
1.8.5.3.493.gb139ac2

[PATCHv2 1/4] zram: drop `init_done' struct zram member

[Sergey Senozhatsky]

Introduce init_done() helper function which allows us to drop
`init_done' struct zram member. init_done() uses the fact that
->init_done == 1 equals to ->meta != NULL.

Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 21 +++++++++++----------
 drivers/block/zram/zram_drv.h |  1 -
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 011e55d..c323e05 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -42,6 +42,11 @@ static struct zram *zram_devices;
 /* Module params (documentation at end) */
 static unsigned int num_devices = 1;
 
+static inline int init_done(struct zram *zram)
+{
+	return zram->meta != NULL;
+}
+
 static inline struct zram *dev_to_zram(struct device *dev)
 {
 	return (struct zram *)dev_to_disk(dev)->private_data;
@@ -60,7 +65,7 @@ static ssize_t initstate_show(struct device *dev,
 {
 	struct zram *zram = dev_to_zram(dev);
 
-	return sprintf(buf, "%u\n", zram->init_done);
+	return sprintf(buf, "%u\n", init_done(zram));
 }
 
 static ssize_t num_reads_show(struct device *dev,
@@ -133,7 +138,7 @@ static ssize_t mem_used_total_show(struct device *dev,
 	struct zram_meta *meta = zram->meta;
 
 	down_read(&zram->init_lock);
-	if (zram->init_done)
+	if (init_done(zram))
 		val = zs_get_total_size_bytes(meta->mem_pool);
 	up_read(&zram->init_lock);
 
@@ -546,14 +551,12 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
 	struct zram_meta *meta;
 
 	down_write(&zram->init_lock);
-	if (!zram->init_done) {
+	if (!init_done(zram)) {
 		up_write(&zram->init_lock);
 		return;
 	}
 
 	meta = zram->meta;
-	zram->init_done = 0;
-
 	/* Free all pages that are still in this zram device */
 	for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
 		unsigned long handle = meta->table[index].handle;
@@ -594,8 +597,6 @@ static void zram_init_device(struct zram *zram, struct zram_meta *meta)
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 
 	zram->meta = meta;
-	zram->init_done = 1;
-
 	pr_debug("Initialization done!\n");
 }
 
@@ -613,7 +614,7 @@ static ssize_t disksize_store(struct device *dev,
 	disksize = PAGE_ALIGN(disksize);
 	meta = zram_meta_alloc(disksize);
 	down_write(&zram->init_lock);
-	if (zram->init_done) {
+	if (init_done(zram)) {
 		up_write(&zram->init_lock);
 		zram_meta_free(meta);
 		pr_info("Cannot change disksize for initialized device\n");
@@ -734,7 +735,7 @@ static void zram_make_request(struct request_queue *queue, struct bio *bio)
 	struct zram *zram = queue->queuedata;
 
 	down_read(&zram->init_lock);
-	if (unlikely(!zram->init_done))
+	if (unlikely(!init_done(zram)))
 		goto error;
 
 	if (!valid_io_request(zram, bio)) {
@@ -857,7 +858,7 @@ static int create_device(struct zram *zram, int device_id)
 		goto out_free_disk;
 	}
 
-	zram->init_done = 0;
+	zram->meta = NULL;
 	return 0;
 
 out_free_disk:
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index ad8aa35..e81e9cd 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -95,7 +95,6 @@ struct zram {
 	struct zram_meta *meta;
 	struct request_queue *queue;
 	struct gendisk *disk;
-	int init_done;
 	/* Prevent concurrent execution of device init, reset and R/W request */
 	struct rw_semaphore init_lock;
 	/*
-- 
1.8.5.3.493.gb139ac2

[PATCHv2 2/4] zram: do not pass rw argument to __zram_make_request()

[Sergey Senozhatsky]

Do not pass rw argument down the __zram_make_request() -> zram_bvec_rw()
chain, decode it in zram_bvec_rw() instead. Besides, this is the place
where we distinguish READ and WRITE bio data directions, so account zram
RW stats here, instead of __zram_make_request(). This also allows to account
a real number of zram READ/WRITE operations, not just requests (single RW
request may cause a number of zram RW ops with separate locking,
compression/decompression, etc).

v2: do not check for READA return code. noted by Jerome Marchand.

Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index c323e05..b0bcb7e 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -533,14 +533,18 @@ out:
 }
 
 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
-			int offset, struct bio *bio, int rw)
+			int offset, struct bio *bio)
 {
 	int ret;
+	int rw = bio_data_dir(bio);
 
-	if (rw == READ)
+	if (rw == READ) {
+		atomic64_inc(&zram->stats.num_reads);
 		ret = zram_bvec_read(zram, bvec, index, offset, bio);
-	else
+	} else {
+		atomic64_inc(&zram->stats.num_writes);
 		ret = zram_bvec_write(zram, bvec, index, offset);
+	}
 
 	return ret;
 }
@@ -670,22 +674,13 @@ out:
 	return ret;
 }
 
-static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
+static void __zram_make_request(struct zram *zram, struct bio *bio)
 {
 	int offset;
 	u32 index;
 	struct bio_vec bvec;
 	struct bvec_iter iter;
 
-	switch (rw) {
-	case READ:
-		atomic64_inc(&zram->stats.num_reads);
-		break;
-	case WRITE:
-		atomic64_inc(&zram->stats.num_writes);
-		break;
-	}
-
 	index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
 	offset = (bio->bi_iter.bi_sector &
 		  (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
@@ -704,16 +699,15 @@ static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
 			bv.bv_len = max_transfer_size;
 			bv.bv_offset = bvec.bv_offset;
 
-			if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
+			if (zram_bvec_rw(zram, &bv, index, offset, bio) < 0)
 				goto out;
 
 			bv.bv_len = bvec.bv_len - max_transfer_size;
 			bv.bv_offset += max_transfer_size;
-			if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
+			if (zram_bvec_rw(zram, &bv, index + 1, 0, bio) < 0)
 				goto out;
 		} else
-			if (zram_bvec_rw(zram, &bvec, index, offset, bio, rw)
-			    < 0)
+			if (zram_bvec_rw(zram, &bvec, index, offset, bio) < 0)
 				goto out;
 
 		update_position(&index, &offset, &bvec);
@@ -743,7 +737,7 @@ static void zram_make_request(struct request_queue *queue, struct bio *bio)
 		goto error;
 	}
 
-	__zram_make_request(zram, bio, bio_data_dir(bio));
+	__zram_make_request(zram, bio);
 	up_read(&zram->init_lock);
 
 	return;
-- 
1.8.5.3.493.gb139ac2

[PATCHv2 3/4] zram: rework reported to end-user zram statistics

[Sergey Senozhatsky]

1) Introduce ZRAM_ATTR_RO macro to generate zram atomic64_t stats
`show' functions and reduce code duplication.

2) Remove `good' and `bad' compressed sub-requests stats. RW request may
cause a number of RW sub-requests. zram used to account `good' compressed
sub-queries (with compressed size less than 50% of original size), `bad'
compressed sub-queries (with compressed size greater that 75% of original
size), leaving sub-requests with compression size between 50% and 75% of
original size not accounted and not reported. zram already accounts each
sub-request's compression size so we can calculate real device compression
ratio.

Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 163 ++++++++++++------------------------------
 drivers/block/zram/zram_drv.h |  17 ++---
 2 files changed, 51 insertions(+), 129 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index b0bcb7e..6eb2155 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -42,6 +42,17 @@ static struct zram *zram_devices;
 /* Module params (documentation at end) */
 static unsigned int num_devices = 1;
 
+#define ZRAM_ATTR_RO(name)						\
+static ssize_t zram_attr_##name##_show(struct device *d,		\
+				struct device_attribute *attr, char *b)	\
+{									\
+	struct zram *zram = dev_to_zram(d);				\
+	return sprintf(b, "%llu\n",					\
+		(u64)atomic64_read(&zram->stats.name));			\
+}									\
+static struct device_attribute dev_attr_##name =			\
+	__ATTR(name, S_IRUGO, zram_attr_##name##_show, NULL);
+
 static inline int init_done(struct zram *zram)
 {
 	return zram->meta != NULL;
@@ -52,97 +63,36 @@ static inline struct zram *dev_to_zram(struct device *dev)
 	return (struct zram *)dev_to_disk(dev)->private_data;
 }
 
-static ssize_t disksize_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct zram *zram = dev_to_zram(dev);
-
-	return sprintf(buf, "%llu\n", zram->disksize);
-}
-
-static ssize_t initstate_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct zram *zram = dev_to_zram(dev);
-
-	return sprintf(buf, "%u\n", init_done(zram));
-}
-
-static ssize_t num_reads_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct zram *zram = dev_to_zram(dev);
-
-	return sprintf(buf, "%llu\n",
-			(u64)atomic64_read(&zram->stats.num_reads));
-}
-
-static ssize_t num_writes_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct zram *zram = dev_to_zram(dev);
-
-	return sprintf(buf, "%llu\n",
-			(u64)atomic64_read(&zram->stats.num_writes));
-}
-
-static ssize_t invalid_io_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct zram *zram = dev_to_zram(dev);
-
-	return sprintf(buf, "%llu\n",
-			(u64)atomic64_read(&zram->stats.invalid_io));
-}
-
-static ssize_t notify_free_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct zram *zram = dev_to_zram(dev);
-
-	return sprintf(buf, "%llu\n",
-			(u64)atomic64_read(&zram->stats.notify_free));
-}
-
-static ssize_t zero_pages_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct zram *zram = dev_to_zram(dev);
-
-	return sprintf(buf, "%u\n", atomic_read(&zram->stats.pages_zero));
-}
-
-static ssize_t orig_data_size_show(struct device *dev,
+static ssize_t memory_used_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
+	u64 val = 0;
 	struct zram *zram = dev_to_zram(dev);
+	struct zram_meta *meta = zram->meta;
 
-	return sprintf(buf, "%llu\n",
-		(u64)(atomic_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
+	down_read(&zram->init_lock);
+	if (init_done(zram))
+		val = zs_get_total_size_bytes(meta->mem_pool);
+	up_read(&zram->init_lock);
+	return sprintf(buf, "%llu\n", val);
 }
 
-static ssize_t compr_data_size_show(struct device *dev,
+static ssize_t disksize_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct zram *zram = dev_to_zram(dev);
-
-	return sprintf(buf, "%llu\n",
-			(u64)atomic64_read(&zram->stats.compr_size));
+	return sprintf(buf, "%llu\n", zram->disksize);
 }
 
-static ssize_t mem_used_total_show(struct device *dev,
+static ssize_t initstate_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
-	u64 val = 0;
+	u32 val = 0;
 	struct zram *zram = dev_to_zram(dev);
-	struct zram_meta *meta = zram->meta;
-
 	down_read(&zram->init_lock);
-	if (init_done(zram))
-		val = zs_get_total_size_bytes(meta->mem_pool);
+	val = init_done(zram);
 	up_read(&zram->init_lock);
-
-	return sprintf(buf, "%llu\n", val);
+	return sprintf(buf, "%u\n", val);
 }
 
 /* flag operations needs meta->tb_lock */
@@ -293,7 +243,6 @@ static void zram_free_page(struct zram *zram, size_t index)
 {
 	struct zram_meta *meta = zram->meta;
 	unsigned long handle = meta->table[index].handle;
-	u16 size = meta->table[index].size;
 
 	if (unlikely(!handle)) {
 		/*
@@ -302,21 +251,15 @@ 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.pages_zero);
 		}
 		return;
 	}
 
-	if (unlikely(size > max_zpage_size))
-		atomic_dec(&zram->stats.bad_compress);
-
 	zs_free(meta->mem_pool, handle);
 
-	if (size <= PAGE_SIZE / 2)
-		atomic_dec(&zram->stats.good_compress);
-
-	atomic64_sub(meta->table[index].size, &zram->stats.compr_size);
-	atomic_dec(&zram->stats.pages_stored);
+	atomic64_sub(meta->table[index].size, &zram->stats.compressed_size);
+	atomic64_dec(&zram->stats.pages_stored);
 
 	meta->table[index].handle = 0;
 	meta->table[index].size = 0;
@@ -459,7 +402,7 @@ 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.pages_zero);
 		ret = 0;
 		goto out;
 	}
@@ -478,7 +421,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 	}
 
 	if (unlikely(clen > max_zpage_size)) {
-		atomic_inc(&zram->stats.bad_compress);
 		clen = PAGE_SIZE;
 		src = NULL;
 		if (is_partial_io(bvec))
@@ -516,11 +458,8 @@ 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);
-	if (clen <= PAGE_SIZE / 2)
-		atomic_inc(&zram->stats.good_compress);
-
+	atomic64_add(clen, &zram->stats.compressed_size);
+	atomic64_inc(&zram->stats.pages_stored);
 out:
 	if (locked)
 		mutex_unlock(&meta->buffer_lock);
@@ -583,23 +522,8 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
 
 static void zram_init_device(struct zram *zram, struct zram_meta *meta)
 {
-	if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
-		pr_info(
-		"There is little point creating a zram of greater than "
-		"twice the size of memory since we expect a 2:1 compression "
-		"ratio. Note that zram uses about 0.1%% of the size of "
-		"the disk when not in use so a huge zram is "
-		"wasteful.\n"
-		"\tMemory Size: %lu kB\n"
-		"\tSize you selected: %llu kB\n"
-		"Continuing anyway ...\n",
-		(totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
-		);
-	}
-
 	/* zram devices sort of resembles non-rotational disks */
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
-
 	zram->meta = meta;
 	pr_debug("Initialization done!\n");
 }
@@ -771,14 +695,15 @@ static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
 		disksize_show, disksize_store);
 static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
 static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
-static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
-static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);
-static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
-static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
-static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
-static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
-static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
-static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
+static DEVICE_ATTR(memory_used, S_IRUGO, memory_used_show, NULL);
+
+ZRAM_ATTR_RO(num_reads);
+ZRAM_ATTR_RO(num_writes);
+ZRAM_ATTR_RO(pages_stored);
+ZRAM_ATTR_RO(invalid_io);
+ZRAM_ATTR_RO(notify_free);
+ZRAM_ATTR_RO(pages_zero);
+ZRAM_ATTR_RO(compressed_size);
 
 static struct attribute *zram_disk_attrs[] = {
 	&dev_attr_disksize.attr,
@@ -786,12 +711,12 @@ static struct attribute *zram_disk_attrs[] = {
 	&dev_attr_reset.attr,
 	&dev_attr_num_reads.attr,
 	&dev_attr_num_writes.attr,
+	&dev_attr_pages_stored.attr,
 	&dev_attr_invalid_io.attr,
 	&dev_attr_notify_free.attr,
-	&dev_attr_zero_pages.attr,
-	&dev_attr_orig_data_size.attr,
-	&dev_attr_compr_data_size.attr,
-	&dev_attr_mem_used_total.attr,
+	&dev_attr_pages_zero.attr,
+	&dev_attr_compressed_size.attr,
+	&dev_attr_memory_used.attr,
 	NULL,
 };
 
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index e81e9cd..277023d 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -64,22 +64,19 @@ enum zram_pageflags {
 struct table {
 	unsigned long handle;
 	u16 size;	/* object size (excluding header) */
-	u8 count;	/* object ref count (not yet used) */
-	u8 flags;
+	u16 flags;
 } __aligned(4);
 
 struct zram_stats {
-	atomic64_t compr_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 num_writes;	/* number of writes */
+	atomic64_t num_reads;	/* number of reads */
+	atomic64_t pages_stored;	/* no. of pages currently stored */
+	atomic64_t compressed_size;	/* compressed size of pages stored */
+	atomic64_t pages_zero;		/* no. of zero filled pages */
+	atomic64_t failed_reads;	/* no. of failed reads */
 	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 */
-	atomic_t good_compress;	/* % of pages with compression ratio<=50% */
-	atomic_t bad_compress;	/* % of pages with compression ratio>=75% */
 };
 
 struct zram_meta {
-- 
1.8.5.3.493.gb139ac2

[PATCHv2 4/4] zram: report failed read and writes stats

[Sergey Senozhatsky]

zram accounted but did not report numbers of failed read
and write queries. make these stats available as failed_reads
and failed_writes attrs.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 6eb2155..ce00d47 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -699,6 +699,8 @@ static DEVICE_ATTR(memory_used, S_IRUGO, memory_used_show, NULL);
 
 ZRAM_ATTR_RO(num_reads);
 ZRAM_ATTR_RO(num_writes);
+ZRAM_ATTR_RO(failed_reads);
+ZRAM_ATTR_RO(failed_writes);
 ZRAM_ATTR_RO(pages_stored);
 ZRAM_ATTR_RO(invalid_io);
 ZRAM_ATTR_RO(notify_free);
@@ -711,6 +713,8 @@ static struct attribute *zram_disk_attrs[] = {
 	&dev_attr_reset.attr,
 	&dev_attr_num_reads.attr,
 	&dev_attr_num_writes.attr,
+	&dev_attr_failed_reads.attr,
+	&dev_attr_failed_writes.attr,
 	&dev_attr_pages_stored.attr,
 	&dev_attr_invalid_io.attr,
 	&dev_attr_notify_free.attr,
-- 
1.8.5.3.493.gb139ac2

Re: [PATCHv2 3/4] zram: rework reported to end-user zram statistics

[Minchan Kim]

Hello Sergey,

On Wed, Jan 15, 2014 at 01:16:16PM +0300, Sergey Senozhatsky wrote:
> 1) Introduce ZRAM_ATTR_RO macro to generate zram atomic64_t stats
> `show' functions and reduce code duplication.
> 
> 2) Remove `good' and `bad' compressed sub-requests stats. RW request may
> cause a number of RW sub-requests. zram used to account `good' compressed
> sub-queries (with compressed size less than 50% of original size), `bad'
> compressed sub-queries (with compressed size greater that 75% of original
> size), leaving sub-requests with compression size between 50% and 75% of
> original size not accounted and not reported. zram already accounts each
> sub-request's compression size so we can calculate real device compression
> ratio.
> 
> Acked-by: Minchan Kim <minchan@kernel.org>

I didn't give any Acked in this patch.
If I made you confused, Sorry about that.

This patch did more than thing you mentioned in desription.

1. Introduce macro to remove code duplication

   It's really good.

2. Change atomic_t with atomic64_t

   At a first look, I didn't want it because lots of custormer for zram
   are still 32bit machines so their cost would be increased a bit due to
   any locking facility like cmpxchg on some architectures.

   Having said that, I will support your cleanup patch now and then
   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.

   So, please add this comment for future just in case of forgetting.
   
3. Remove unreported some stat

   Looks good to me.

4. Changing name of some stat

   I couldn't understand what's the gain because I'm happy with
   orig_data_size and compr_data_size now.

5. Removed zram_init_device's warning

   Why? This patch doesn't include any justification.

6. Removed unused field of enum zram_pageflags

   Looks good to me.

Please, separate it with each patches so let's focus one by one.


> Acked-by: Jerome Marchand <jmarchan@redhat.com>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> ---
>  drivers/block/zram/zram_drv.c | 163 ++++++++++++------------------------------
>  drivers/block/zram/zram_drv.h |  17 ++---
>  2 files changed, 51 insertions(+), 129 deletions(-)
> 
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index b0bcb7e..6eb2155 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -42,6 +42,17 @@ static struct zram *zram_devices;
>  /* Module params (documentation at end) */
>  static unsigned int num_devices = 1;
>  
> +#define ZRAM_ATTR_RO(name)						\
> +static ssize_t zram_attr_##name##_show(struct device *d,		\
> +				struct device_attribute *attr, char *b)	\
> +{									\
> +	struct zram *zram = dev_to_zram(d);				\
> +	return sprintf(b, "%llu\n",					\
> +		(u64)atomic64_read(&zram->stats.name));			\
> +}									\
> +static struct device_attribute dev_attr_##name =			\
> +	__ATTR(name, S_IRUGO, zram_attr_##name##_show, NULL);
> +
>  static inline int init_done(struct zram *zram)
>  {
>  	return zram->meta != NULL;
> @@ -52,97 +63,36 @@ static inline struct zram *dev_to_zram(struct device *dev)
>  	return (struct zram *)dev_to_disk(dev)->private_data;
>  }
>  
> -static ssize_t disksize_show(struct device *dev,
> -		struct device_attribute *attr, char *buf)
> -{
> -	struct zram *zram = dev_to_zram(dev);
> -
> -	return sprintf(buf, "%llu\n", zram->disksize);
> -}
> -
> -static ssize_t initstate_show(struct device *dev,
> -		struct device_attribute *attr, char *buf)
> -{
> -	struct zram *zram = dev_to_zram(dev);
> -
> -	return sprintf(buf, "%u\n", init_done(zram));
> -}
> -
> -static ssize_t num_reads_show(struct device *dev,
> -		struct device_attribute *attr, char *buf)
> -{
> -	struct zram *zram = dev_to_zram(dev);
> -
> -	return sprintf(buf, "%llu\n",
> -			(u64)atomic64_read(&zram->stats.num_reads));
> -}
> -
> -static ssize_t num_writes_show(struct device *dev,
> -		struct device_attribute *attr, char *buf)
> -{
> -	struct zram *zram = dev_to_zram(dev);
> -
> -	return sprintf(buf, "%llu\n",
> -			(u64)atomic64_read(&zram->stats.num_writes));
> -}
> -
> -static ssize_t invalid_io_show(struct device *dev,
> -		struct device_attribute *attr, char *buf)
> -{
> -	struct zram *zram = dev_to_zram(dev);
> -
> -	return sprintf(buf, "%llu\n",
> -			(u64)atomic64_read(&zram->stats.invalid_io));
> -}
> -
> -static ssize_t notify_free_show(struct device *dev,
> -		struct device_attribute *attr, char *buf)
> -{
> -	struct zram *zram = dev_to_zram(dev);
> -
> -	return sprintf(buf, "%llu\n",
> -			(u64)atomic64_read(&zram->stats.notify_free));
> -}
> -
> -static ssize_t zero_pages_show(struct device *dev,
> -		struct device_attribute *attr, char *buf)
> -{
> -	struct zram *zram = dev_to_zram(dev);
> -
> -	return sprintf(buf, "%u\n", atomic_read(&zram->stats.pages_zero));
> -}
> -
> -static ssize_t orig_data_size_show(struct device *dev,
> +static ssize_t memory_used_show(struct device *dev,
>  		struct device_attribute *attr, char *buf)
>  {
> +	u64 val = 0;
>  	struct zram *zram = dev_to_zram(dev);
> +	struct zram_meta *meta = zram->meta;
>  
> -	return sprintf(buf, "%llu\n",
> -		(u64)(atomic_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
> +	down_read(&zram->init_lock);
> +	if (init_done(zram))
> +		val = zs_get_total_size_bytes(meta->mem_pool);
> +	up_read(&zram->init_lock);
> +	return sprintf(buf, "%llu\n", val);
>  }
>  
> -static ssize_t compr_data_size_show(struct device *dev,
> +static ssize_t disksize_show(struct device *dev,
>  		struct device_attribute *attr, char *buf)
>  {
>  	struct zram *zram = dev_to_zram(dev);
> -
> -	return sprintf(buf, "%llu\n",
> -			(u64)atomic64_read(&zram->stats.compr_size));
> +	return sprintf(buf, "%llu\n", zram->disksize);
>  }
>  
> -static ssize_t mem_used_total_show(struct device *dev,
> +static ssize_t initstate_show(struct device *dev,
>  		struct device_attribute *attr, char *buf)
>  {
> -	u64 val = 0;
> +	u32 val = 0;
>  	struct zram *zram = dev_to_zram(dev);
> -	struct zram_meta *meta = zram->meta;
> -
>  	down_read(&zram->init_lock);
> -	if (init_done(zram))
> -		val = zs_get_total_size_bytes(meta->mem_pool);
> +	val = init_done(zram);
>  	up_read(&zram->init_lock);
> -
> -	return sprintf(buf, "%llu\n", val);
> +	return sprintf(buf, "%u\n", val);
>  }
>  
>  /* flag operations needs meta->tb_lock */
> @@ -293,7 +243,6 @@ static void zram_free_page(struct zram *zram, size_t index)
>  {
>  	struct zram_meta *meta = zram->meta;
>  	unsigned long handle = meta->table[index].handle;
> -	u16 size = meta->table[index].size;
>  
>  	if (unlikely(!handle)) {
>  		/*
> @@ -302,21 +251,15 @@ 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.pages_zero);
>  		}
>  		return;
>  	}
>  
> -	if (unlikely(size > max_zpage_size))
> -		atomic_dec(&zram->stats.bad_compress);
> -
>  	zs_free(meta->mem_pool, handle);
>  
> -	if (size <= PAGE_SIZE / 2)
> -		atomic_dec(&zram->stats.good_compress);
> -
> -	atomic64_sub(meta->table[index].size, &zram->stats.compr_size);
> -	atomic_dec(&zram->stats.pages_stored);
> +	atomic64_sub(meta->table[index].size, &zram->stats.compressed_size);
> +	atomic64_dec(&zram->stats.pages_stored);
>  
>  	meta->table[index].handle = 0;
>  	meta->table[index].size = 0;
> @@ -459,7 +402,7 @@ 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.pages_zero);
>  		ret = 0;
>  		goto out;
>  	}
> @@ -478,7 +421,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
>  	}
>  
>  	if (unlikely(clen > max_zpage_size)) {
> -		atomic_inc(&zram->stats.bad_compress);
>  		clen = PAGE_SIZE;
>  		src = NULL;
>  		if (is_partial_io(bvec))
> @@ -516,11 +458,8 @@ 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);
> -	if (clen <= PAGE_SIZE / 2)
> -		atomic_inc(&zram->stats.good_compress);
> -
> +	atomic64_add(clen, &zram->stats.compressed_size);
> +	atomic64_inc(&zram->stats.pages_stored);
>  out:
>  	if (locked)
>  		mutex_unlock(&meta->buffer_lock);
> @@ -583,23 +522,8 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
>  
>  static void zram_init_device(struct zram *zram, struct zram_meta *meta)
>  {
> -	if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
> -		pr_info(
> -		"There is little point creating a zram of greater than "
> -		"twice the size of memory since we expect a 2:1 compression "
> -		"ratio. Note that zram uses about 0.1%% of the size of "
> -		"the disk when not in use so a huge zram is "
> -		"wasteful.\n"
> -		"\tMemory Size: %lu kB\n"
> -		"\tSize you selected: %llu kB\n"
> -		"Continuing anyway ...\n",
> -		(totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
> -		);
> -	}
> -
>  	/* zram devices sort of resembles non-rotational disks */
>  	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
> -
>  	zram->meta = meta;
>  	pr_debug("Initialization done!\n");
>  }
> @@ -771,14 +695,15 @@ static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
>  		disksize_show, disksize_store);
>  static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
>  static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
> -static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
> -static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);
> -static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
> -static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
> -static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
> -static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
> -static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
> -static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
> +static DEVICE_ATTR(memory_used, S_IRUGO, memory_used_show, NULL);
> +
> +ZRAM_ATTR_RO(num_reads);
> +ZRAM_ATTR_RO(num_writes);
> +ZRAM_ATTR_RO(pages_stored);
> +ZRAM_ATTR_RO(invalid_io);
> +ZRAM_ATTR_RO(notify_free);
> +ZRAM_ATTR_RO(pages_zero);
> +ZRAM_ATTR_RO(compressed_size);
>  
>  static struct attribute *zram_disk_attrs[] = {
>  	&dev_attr_disksize.attr,
> @@ -786,12 +711,12 @@ static struct attribute *zram_disk_attrs[] = {
>  	&dev_attr_reset.attr,
>  	&dev_attr_num_reads.attr,
>  	&dev_attr_num_writes.attr,
> +	&dev_attr_pages_stored.attr,
>  	&dev_attr_invalid_io.attr,
>  	&dev_attr_notify_free.attr,
> -	&dev_attr_zero_pages.attr,
> -	&dev_attr_orig_data_size.attr,
> -	&dev_attr_compr_data_size.attr,
> -	&dev_attr_mem_used_total.attr,
> +	&dev_attr_pages_zero.attr,
> +	&dev_attr_compressed_size.attr,
> +	&dev_attr_memory_used.attr,
>  	NULL,
>  };
>  
> diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> index e81e9cd..277023d 100644
> --- a/drivers/block/zram/zram_drv.h
> +++ b/drivers/block/zram/zram_drv.h
> @@ -64,22 +64,19 @@ enum zram_pageflags {
>  struct table {
>  	unsigned long handle;
>  	u16 size;	/* object size (excluding header) */
> -	u8 count;	/* object ref count (not yet used) */
> -	u8 flags;
> +	u16 flags;
>  } __aligned(4);
>  
>  struct zram_stats {
> -	atomic64_t compr_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 num_writes;	/* number of writes */
> +	atomic64_t num_reads;	/* number of reads */
> +	atomic64_t pages_stored;	/* no. of pages currently stored */
> +	atomic64_t compressed_size;	/* compressed size of pages stored */
> +	atomic64_t pages_zero;		/* no. of zero filled pages */
> +	atomic64_t failed_reads;	/* no. of failed reads */
>  	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 */
> -	atomic_t good_compress;	/* % of pages with compression ratio<=50% */
> -	atomic_t bad_compress;	/* % of pages with compression ratio>=75% */
>  };
>  
>  struct zram_meta {
> -- 
> 1.8.5.3.493.gb139ac2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

-- 
Kind regards,
Minchan Kim

Re: [PATCHv2 4/4] zram: report failed read and writes stats

[Minchan Kim]

On Wed, Jan 15, 2014 at 01:16:17PM +0300, Sergey Senozhatsky wrote:
> zram accounted but did not report numbers of failed read
> and write queries. make these stats available as failed_reads
> and failed_writes attrs.
> 
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>

-- 
Kind regards,
Minchan Kim

Re: [PATCHv2 3/4] zram: rework reported to end-user zram statistics

[Sergey Senozhatsky]

On (01/16/14 09:56), Minchan Kim wrote:
> Hello Sergey,
> 
> On Wed, Jan 15, 2014 at 01:16:16PM +0300, Sergey Senozhatsky wrote:
> > 1) Introduce ZRAM_ATTR_RO macro to generate zram atomic64_t stats
> > `show' functions and reduce code duplication.
> > 
> > 2) Remove `good' and `bad' compressed sub-requests stats. RW request may
> > cause a number of RW sub-requests. zram used to account `good' compressed
> > sub-queries (with compressed size less than 50% of original size), `bad'
> > compressed sub-queries (with compressed size greater that 75% of original
> > size), leaving sub-requests with compression size between 50% and 75% of
> > original size not accounted and not reported. zram already accounts each
> > sub-request's compression size so we can calculate real device compression
> > ratio.
> > 
> > Acked-by: Minchan Kim <minchan@kernel.org>
> 
> I didn't give any Acked in this patch.
> If I made you confused, Sorry about that.
> 

Hello,

sorry, I misread the situtation.

> This patch did more than thing you mentioned in desription.
> 
> 1. Introduce macro to remove code duplication
> 
>    It's really good.
> 
> 2. Change atomic_t with atomic64_t
> 
>    At a first look, I didn't want it because lots of custormer for zram
>    are still 32bit machines so their cost would be increased a bit due to
>    any locking facility like cmpxchg on some architectures.
> 
>    Having said that, I will support your cleanup patch now and then
>    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.
> 
>    So, please add this comment for future just in case of forgetting.

ok

> 3. Remove unreported some stat
> 
>    Looks good to me.
> 

> 4. Changing name of some stat
> 
>    I couldn't understand what's the gain because I'm happy with
>    orig_data_size and compr_data_size now.
> 

well, compressed_size contains regular english words and thus a regular
user can easily understand it. compr_data_size looks like a variable name.
I think I'll drop this at the moment.

> 5. Removed zram_init_device's warning
> 
>    Why? This patch doesn't include any justification.
> 

I think I'll drop this part at the moment. the motivation for this
cleanup was that, imho, such big informative warnings are part of
documentation, not the source code.

	-ss

> 6. Removed unused field of enum zram_pageflags
> 
>    Looks good to me.
> 
> Please, separate it with each patches so let's focus one by one.
> 
> 
> > Acked-by: Jerome Marchand <jmarchan@redhat.com>
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> > ---
> >  drivers/block/zram/zram_drv.c | 163 ++++++++++++------------------------------
> >  drivers/block/zram/zram_drv.h |  17 ++---
> >  2 files changed, 51 insertions(+), 129 deletions(-)
> > 
> > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> > index b0bcb7e..6eb2155 100644
> > --- a/drivers/block/zram/zram_drv.c
> > +++ b/drivers/block/zram/zram_drv.c
> > @@ -42,6 +42,17 @@ static struct zram *zram_devices;
> >  /* Module params (documentation at end) */
> >  static unsigned int num_devices = 1;
> >  
> > +#define ZRAM_ATTR_RO(name)						\
> > +static ssize_t zram_attr_##name##_show(struct device *d,		\
> > +				struct device_attribute *attr, char *b)	\
> > +{									\
> > +	struct zram *zram = dev_to_zram(d);				\
> > +	return sprintf(b, "%llu\n",					\
> > +		(u64)atomic64_read(&zram->stats.name));			\
> > +}									\
> > +static struct device_attribute dev_attr_##name =			\
> > +	__ATTR(name, S_IRUGO, zram_attr_##name##_show, NULL);
> > +
> >  static inline int init_done(struct zram *zram)
> >  {
> >  	return zram->meta != NULL;
> > @@ -52,97 +63,36 @@ static inline struct zram *dev_to_zram(struct device *dev)
> >  	return (struct zram *)dev_to_disk(dev)->private_data;
> >  }
> >  
> > -static ssize_t disksize_show(struct device *dev,
> > -		struct device_attribute *attr, char *buf)
> > -{
> > -	struct zram *zram = dev_to_zram(dev);
> > -
> > -	return sprintf(buf, "%llu\n", zram->disksize);
> > -}
> > -
> > -static ssize_t initstate_show(struct device *dev,
> > -		struct device_attribute *attr, char *buf)
> > -{
> > -	struct zram *zram = dev_to_zram(dev);
> > -
> > -	return sprintf(buf, "%u\n", init_done(zram));
> > -}
> > -
> > -static ssize_t num_reads_show(struct device *dev,
> > -		struct device_attribute *attr, char *buf)
> > -{
> > -	struct zram *zram = dev_to_zram(dev);
> > -
> > -	return sprintf(buf, "%llu\n",
> > -			(u64)atomic64_read(&zram->stats.num_reads));
> > -}
> > -
> > -static ssize_t num_writes_show(struct device *dev,
> > -		struct device_attribute *attr, char *buf)
> > -{
> > -	struct zram *zram = dev_to_zram(dev);
> > -
> > -	return sprintf(buf, "%llu\n",
> > -			(u64)atomic64_read(&zram->stats.num_writes));
> > -}
> > -
> > -static ssize_t invalid_io_show(struct device *dev,
> > -		struct device_attribute *attr, char *buf)
> > -{
> > -	struct zram *zram = dev_to_zram(dev);
> > -
> > -	return sprintf(buf, "%llu\n",
> > -			(u64)atomic64_read(&zram->stats.invalid_io));
> > -}
> > -
> > -static ssize_t notify_free_show(struct device *dev,
> > -		struct device_attribute *attr, char *buf)
> > -{
> > -	struct zram *zram = dev_to_zram(dev);
> > -
> > -	return sprintf(buf, "%llu\n",
> > -			(u64)atomic64_read(&zram->stats.notify_free));
> > -}
> > -
> > -static ssize_t zero_pages_show(struct device *dev,
> > -		struct device_attribute *attr, char *buf)
> > -{
> > -	struct zram *zram = dev_to_zram(dev);
> > -
> > -	return sprintf(buf, "%u\n", atomic_read(&zram->stats.pages_zero));
> > -}
> > -
> > -static ssize_t orig_data_size_show(struct device *dev,
> > +static ssize_t memory_used_show(struct device *dev,
> >  		struct device_attribute *attr, char *buf)
> >  {
> > +	u64 val = 0;
> >  	struct zram *zram = dev_to_zram(dev);
> > +	struct zram_meta *meta = zram->meta;
> >  
> > -	return sprintf(buf, "%llu\n",
> > -		(u64)(atomic_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
> > +	down_read(&zram->init_lock);
> > +	if (init_done(zram))
> > +		val = zs_get_total_size_bytes(meta->mem_pool);
> > +	up_read(&zram->init_lock);
> > +	return sprintf(buf, "%llu\n", val);
> >  }
> >  
> > -static ssize_t compr_data_size_show(struct device *dev,
> > +static ssize_t disksize_show(struct device *dev,
> >  		struct device_attribute *attr, char *buf)
> >  {
> >  	struct zram *zram = dev_to_zram(dev);
> > -
> > -	return sprintf(buf, "%llu\n",
> > -			(u64)atomic64_read(&zram->stats.compr_size));
> > +	return sprintf(buf, "%llu\n", zram->disksize);
> >  }
> >  
> > -static ssize_t mem_used_total_show(struct device *dev,
> > +static ssize_t initstate_show(struct device *dev,
> >  		struct device_attribute *attr, char *buf)
> >  {
> > -	u64 val = 0;
> > +	u32 val = 0;
> >  	struct zram *zram = dev_to_zram(dev);
> > -	struct zram_meta *meta = zram->meta;
> > -
> >  	down_read(&zram->init_lock);
> > -	if (init_done(zram))
> > -		val = zs_get_total_size_bytes(meta->mem_pool);
> > +	val = init_done(zram);
> >  	up_read(&zram->init_lock);
> > -
> > -	return sprintf(buf, "%llu\n", val);
> > +	return sprintf(buf, "%u\n", val);
> >  }
> >  
> >  /* flag operations needs meta->tb_lock */
> > @@ -293,7 +243,6 @@ static void zram_free_page(struct zram *zram, size_t index)
> >  {
> >  	struct zram_meta *meta = zram->meta;
> >  	unsigned long handle = meta->table[index].handle;
> > -	u16 size = meta->table[index].size;
> >  
> >  	if (unlikely(!handle)) {
> >  		/*
> > @@ -302,21 +251,15 @@ 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.pages_zero);
> >  		}
> >  		return;
> >  	}
> >  
> > -	if (unlikely(size > max_zpage_size))
> > -		atomic_dec(&zram->stats.bad_compress);
> > -
> >  	zs_free(meta->mem_pool, handle);
> >  
> > -	if (size <= PAGE_SIZE / 2)
> > -		atomic_dec(&zram->stats.good_compress);
> > -
> > -	atomic64_sub(meta->table[index].size, &zram->stats.compr_size);
> > -	atomic_dec(&zram->stats.pages_stored);
> > +	atomic64_sub(meta->table[index].size, &zram->stats.compressed_size);
> > +	atomic64_dec(&zram->stats.pages_stored);
> >  
> >  	meta->table[index].handle = 0;
> >  	meta->table[index].size = 0;
> > @@ -459,7 +402,7 @@ 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.pages_zero);
> >  		ret = 0;
> >  		goto out;
> >  	}
> > @@ -478,7 +421,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> >  	}
> >  
> >  	if (unlikely(clen > max_zpage_size)) {
> > -		atomic_inc(&zram->stats.bad_compress);
> >  		clen = PAGE_SIZE;
> >  		src = NULL;
> >  		if (is_partial_io(bvec))
> > @@ -516,11 +458,8 @@ 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);
> > -	if (clen <= PAGE_SIZE / 2)
> > -		atomic_inc(&zram->stats.good_compress);
> > -
> > +	atomic64_add(clen, &zram->stats.compressed_size);
> > +	atomic64_inc(&zram->stats.pages_stored);
> >  out:
> >  	if (locked)
> >  		mutex_unlock(&meta->buffer_lock);
> > @@ -583,23 +522,8 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
> >  
> >  static void zram_init_device(struct zram *zram, struct zram_meta *meta)
> >  {
> > -	if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
> > -		pr_info(
> > -		"There is little point creating a zram of greater than "
> > -		"twice the size of memory since we expect a 2:1 compression "
> > -		"ratio. Note that zram uses about 0.1%% of the size of "
> > -		"the disk when not in use so a huge zram is "
> > -		"wasteful.\n"
> > -		"\tMemory Size: %lu kB\n"
> > -		"\tSize you selected: %llu kB\n"
> > -		"Continuing anyway ...\n",
> > -		(totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
> > -		);
> > -	}
> > -
> >  	/* zram devices sort of resembles non-rotational disks */
> >  	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
> > -
> >  	zram->meta = meta;
> >  	pr_debug("Initialization done!\n");
> >  }
> > @@ -771,14 +695,15 @@ static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
> >  		disksize_show, disksize_store);
> >  static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
> >  static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
> > -static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
> > -static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);
> > -static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
> > -static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
> > -static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
> > -static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
> > -static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
> > -static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
> > +static DEVICE_ATTR(memory_used, S_IRUGO, memory_used_show, NULL);
> > +
> > +ZRAM_ATTR_RO(num_reads);
> > +ZRAM_ATTR_RO(num_writes);
> > +ZRAM_ATTR_RO(pages_stored);
> > +ZRAM_ATTR_RO(invalid_io);
> > +ZRAM_ATTR_RO(notify_free);
> > +ZRAM_ATTR_RO(pages_zero);
> > +ZRAM_ATTR_RO(compressed_size);
> >  
> >  static struct attribute *zram_disk_attrs[] = {
> >  	&dev_attr_disksize.attr,
> > @@ -786,12 +711,12 @@ static struct attribute *zram_disk_attrs[] = {
> >  	&dev_attr_reset.attr,
> >  	&dev_attr_num_reads.attr,
> >  	&dev_attr_num_writes.attr,
> > +	&dev_attr_pages_stored.attr,
> >  	&dev_attr_invalid_io.attr,
> >  	&dev_attr_notify_free.attr,
> > -	&dev_attr_zero_pages.attr,
> > -	&dev_attr_orig_data_size.attr,
> > -	&dev_attr_compr_data_size.attr,
> > -	&dev_attr_mem_used_total.attr,
> > +	&dev_attr_pages_zero.attr,
> > +	&dev_attr_compressed_size.attr,
> > +	&dev_attr_memory_used.attr,
> >  	NULL,
> >  };
> >  
> > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> > index e81e9cd..277023d 100644
> > --- a/drivers/block/zram/zram_drv.h
> > +++ b/drivers/block/zram/zram_drv.h
> > @@ -64,22 +64,19 @@ enum zram_pageflags {
> >  struct table {
> >  	unsigned long handle;
> >  	u16 size;	/* object size (excluding header) */
> > -	u8 count;	/* object ref count (not yet used) */
> > -	u8 flags;
> > +	u16 flags;
> >  } __aligned(4);
> >  
> >  struct zram_stats {
> > -	atomic64_t compr_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 num_writes;	/* number of writes */
> > +	atomic64_t num_reads;	/* number of reads */
> > +	atomic64_t pages_stored;	/* no. of pages currently stored */
> > +	atomic64_t compressed_size;	/* compressed size of pages stored */
> > +	atomic64_t pages_zero;		/* no. of zero filled pages */
> > +	atomic64_t failed_reads;	/* no. of failed reads */
> >  	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 */
> > -	atomic_t good_compress;	/* % of pages with compression ratio<=50% */
> > -	atomic_t bad_compress;	/* % of pages with compression ratio>=75% */
> >  };
> >  
> >  struct zram_meta {
> > -- 
> > 1.8.5.3.493.gb139ac2
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> 
> -- 
> Kind regards,
> Minchan Kim
> 

Re: [PATCHv2 3/4] zram: rework reported to end-user zram statistics

[Jerome Marchand]

On 01/16/2014 09:46 AM, Sergey Senozhatsky wrote:
> On (01/16/14 09:56), Minchan Kim wrote:
>> Hello Sergey,
>>
>> On Wed, Jan 15, 2014 at 01:16:16PM +0300, Sergey Senozhatsky wrote:
>>> 1) Introduce ZRAM_ATTR_RO macro to generate zram atomic64_t stats
>>> `show' functions and reduce code duplication.
>>>
>>> 2) Remove `good' and `bad' compressed sub-requests stats. RW request may
>>> cause a number of RW sub-requests. zram used to account `good' compressed
>>> sub-queries (with compressed size less than 50% of original size), `bad'
>>> compressed sub-queries (with compressed size greater that 75% of original
>>> size), leaving sub-requests with compression size between 50% and 75% of
>>> original size not accounted and not reported. zram already accounts each
>>> sub-request's compression size so we can calculate real device compression
>>> ratio.
>>>
>>> Acked-by: Minchan Kim <minchan@kernel.org>
>>
>> I didn't give any Acked in this patch.
>> If I made you confused, Sorry about that.
>>
> 
> Hello,
> 
> sorry, I misread the situtation.

Now that Minchan draw my attention to it: neither did I.

> 
>> This patch did more than thing you mentioned in desription.
>>
>> 1. Introduce macro to remove code duplication
>>
>>    It's really good.

No argument here.

>>
>> 2. Change atomic_t with atomic64_t
>>
>>    At a first look, I didn't want it because lots of custormer for zram
>>    are still 32bit machines so their cost would be increased a bit due to
>>    any locking facility like cmpxchg on some architectures.
>>
>>    Having said that, I will support your cleanup patch now and then
>>    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.
>>
>>    So, please add this comment for future just in case of forgetting.
> 
> ok
> 
>> 3. Remove unreported some stat
>>
>>    Looks good to me.

To me too.

>>
> 
>> 4. Changing name of some stat
>>
>>    I couldn't understand what's the gain because I'm happy with
>>    orig_data_size and compr_data_size now.
>>
> 
> well, compressed_size contains regular english words and thus a regular
> user can easily understand it. compr_data_size looks like a variable name.
> I think I'll drop this at the moment.

I think that anybody who is going to read this stats will know that zram is
about compression and understand these abbreviations. I also like the fact
that they are both expressed in bytes, unlike the couple pages_store /
compressed_size.

> 
>> 5. Removed zram_init_device's warning
>>
>>    Why? This patch doesn't include any justification.
>>
> 
> I think I'll drop this part at the moment. the motivation for this
> cleanup was that, imho, such big informative warnings are part of
> documentation, not the source code.

Yet you didn't update the documentation.

Jerome

> 
> 	-ss
> 
>> 6. Removed unused field of enum zram_pageflags
>>
>>    Looks good to me.
>>
>> Please, separate it with each patches so let's focus one by one.
>>
>>
>>> Acked-by: Jerome Marchand <jmarchan@redhat.com>
>>> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
>>> ---
>>>  drivers/block/zram/zram_drv.c | 163 ++++++++++++------------------------------
>>>  drivers/block/zram/zram_drv.h |  17 ++---
>>>  2 files changed, 51 insertions(+), 129 deletions(-)
>>>
>>> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
>>> index b0bcb7e..6eb2155 100644
>>> --- a/drivers/block/zram/zram_drv.c
>>> +++ b/drivers/block/zram/zram_drv.c
>>> @@ -42,6 +42,17 @@ static struct zram *zram_devices;
>>>  /* Module params (documentation at end) */
>>>  static unsigned int num_devices = 1;
>>>  
>>> +#define ZRAM_ATTR_RO(name)						\
>>> +static ssize_t zram_attr_##name##_show(struct device *d,		\
>>> +				struct device_attribute *attr, char *b)	\
>>> +{									\
>>> +	struct zram *zram = dev_to_zram(d);				\
>>> +	return sprintf(b, "%llu\n",					\
>>> +		(u64)atomic64_read(&zram->stats.name));			\
>>> +}									\
>>> +static struct device_attribute dev_attr_##name =			\
>>> +	__ATTR(name, S_IRUGO, zram_attr_##name##_show, NULL);
>>> +
>>>  static inline int init_done(struct zram *zram)
>>>  {
>>>  	return zram->meta != NULL;
>>> @@ -52,97 +63,36 @@ static inline struct zram *dev_to_zram(struct device *dev)
>>>  	return (struct zram *)dev_to_disk(dev)->private_data;
>>>  }
>>>  
>>> -static ssize_t disksize_show(struct device *dev,
>>> -		struct device_attribute *attr, char *buf)
>>> -{
>>> -	struct zram *zram = dev_to_zram(dev);
>>> -
>>> -	return sprintf(buf, "%llu\n", zram->disksize);
>>> -}
>>> -
>>> -static ssize_t initstate_show(struct device *dev,
>>> -		struct device_attribute *attr, char *buf)
>>> -{
>>> -	struct zram *zram = dev_to_zram(dev);
>>> -
>>> -	return sprintf(buf, "%u\n", init_done(zram));
>>> -}
>>> -
>>> -static ssize_t num_reads_show(struct device *dev,
>>> -		struct device_attribute *attr, char *buf)
>>> -{
>>> -	struct zram *zram = dev_to_zram(dev);
>>> -
>>> -	return sprintf(buf, "%llu\n",
>>> -			(u64)atomic64_read(&zram->stats.num_reads));
>>> -}
>>> -
>>> -static ssize_t num_writes_show(struct device *dev,
>>> -		struct device_attribute *attr, char *buf)
>>> -{
>>> -	struct zram *zram = dev_to_zram(dev);
>>> -
>>> -	return sprintf(buf, "%llu\n",
>>> -			(u64)atomic64_read(&zram->stats.num_writes));
>>> -}
>>> -
>>> -static ssize_t invalid_io_show(struct device *dev,
>>> -		struct device_attribute *attr, char *buf)
>>> -{
>>> -	struct zram *zram = dev_to_zram(dev);
>>> -
>>> -	return sprintf(buf, "%llu\n",
>>> -			(u64)atomic64_read(&zram->stats.invalid_io));
>>> -}
>>> -
>>> -static ssize_t notify_free_show(struct device *dev,
>>> -		struct device_attribute *attr, char *buf)
>>> -{
>>> -	struct zram *zram = dev_to_zram(dev);
>>> -
>>> -	return sprintf(buf, "%llu\n",
>>> -			(u64)atomic64_read(&zram->stats.notify_free));
>>> -}
>>> -
>>> -static ssize_t zero_pages_show(struct device *dev,
>>> -		struct device_attribute *attr, char *buf)
>>> -{
>>> -	struct zram *zram = dev_to_zram(dev);
>>> -
>>> -	return sprintf(buf, "%u\n", atomic_read(&zram->stats.pages_zero));
>>> -}
>>> -
>>> -static ssize_t orig_data_size_show(struct device *dev,
>>> +static ssize_t memory_used_show(struct device *dev,
>>>  		struct device_attribute *attr, char *buf)
>>>  {
>>> +	u64 val = 0;
>>>  	struct zram *zram = dev_to_zram(dev);
>>> +	struct zram_meta *meta = zram->meta;
>>>  
>>> -	return sprintf(buf, "%llu\n",
>>> -		(u64)(atomic_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
>>> +	down_read(&zram->init_lock);
>>> +	if (init_done(zram))
>>> +		val = zs_get_total_size_bytes(meta->mem_pool);
>>> +	up_read(&zram->init_lock);
>>> +	return sprintf(buf, "%llu\n", val);
>>>  }
>>>  
>>> -static ssize_t compr_data_size_show(struct device *dev,
>>> +static ssize_t disksize_show(struct device *dev,
>>>  		struct device_attribute *attr, char *buf)
>>>  {
>>>  	struct zram *zram = dev_to_zram(dev);
>>> -
>>> -	return sprintf(buf, "%llu\n",
>>> -			(u64)atomic64_read(&zram->stats.compr_size));
>>> +	return sprintf(buf, "%llu\n", zram->disksize);
>>>  }
>>>  
>>> -static ssize_t mem_used_total_show(struct device *dev,
>>> +static ssize_t initstate_show(struct device *dev,
>>>  		struct device_attribute *attr, char *buf)
>>>  {
>>> -	u64 val = 0;
>>> +	u32 val = 0;
>>>  	struct zram *zram = dev_to_zram(dev);
>>> -	struct zram_meta *meta = zram->meta;
>>> -
>>>  	down_read(&zram->init_lock);
>>> -	if (init_done(zram))
>>> -		val = zs_get_total_size_bytes(meta->mem_pool);
>>> +	val = init_done(zram);
>>>  	up_read(&zram->init_lock);
>>> -
>>> -	return sprintf(buf, "%llu\n", val);
>>> +	return sprintf(buf, "%u\n", val);
>>>  }
>>>  
>>>  /* flag operations needs meta->tb_lock */
>>> @@ -293,7 +243,6 @@ static void zram_free_page(struct zram *zram, size_t index)
>>>  {
>>>  	struct zram_meta *meta = zram->meta;
>>>  	unsigned long handle = meta->table[index].handle;
>>> -	u16 size = meta->table[index].size;
>>>  
>>>  	if (unlikely(!handle)) {
>>>  		/*
>>> @@ -302,21 +251,15 @@ 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.pages_zero);
>>>  		}
>>>  		return;
>>>  	}
>>>  
>>> -	if (unlikely(size > max_zpage_size))
>>> -		atomic_dec(&zram->stats.bad_compress);
>>> -
>>>  	zs_free(meta->mem_pool, handle);
>>>  
>>> -	if (size <= PAGE_SIZE / 2)
>>> -		atomic_dec(&zram->stats.good_compress);
>>> -
>>> -	atomic64_sub(meta->table[index].size, &zram->stats.compr_size);
>>> -	atomic_dec(&zram->stats.pages_stored);
>>> +	atomic64_sub(meta->table[index].size, &zram->stats.compressed_size);
>>> +	atomic64_dec(&zram->stats.pages_stored);
>>>  
>>>  	meta->table[index].handle = 0;
>>>  	meta->table[index].size = 0;
>>> @@ -459,7 +402,7 @@ 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.pages_zero);
>>>  		ret = 0;
>>>  		goto out;
>>>  	}
>>> @@ -478,7 +421,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
>>>  	}
>>>  
>>>  	if (unlikely(clen > max_zpage_size)) {
>>> -		atomic_inc(&zram->stats.bad_compress);
>>>  		clen = PAGE_SIZE;
>>>  		src = NULL;
>>>  		if (is_partial_io(bvec))
>>> @@ -516,11 +458,8 @@ 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);
>>> -	if (clen <= PAGE_SIZE / 2)
>>> -		atomic_inc(&zram->stats.good_compress);
>>> -
>>> +	atomic64_add(clen, &zram->stats.compressed_size);
>>> +	atomic64_inc(&zram->stats.pages_stored);
>>>  out:
>>>  	if (locked)
>>>  		mutex_unlock(&meta->buffer_lock);
>>> @@ -583,23 +522,8 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
>>>  
>>>  static void zram_init_device(struct zram *zram, struct zram_meta *meta)
>>>  {
>>> -	if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
>>> -		pr_info(
>>> -		"There is little point creating a zram of greater than "
>>> -		"twice the size of memory since we expect a 2:1 compression "
>>> -		"ratio. Note that zram uses about 0.1%% of the size of "
>>> -		"the disk when not in use so a huge zram is "
>>> -		"wasteful.\n"
>>> -		"\tMemory Size: %lu kB\n"
>>> -		"\tSize you selected: %llu kB\n"
>>> -		"Continuing anyway ...\n",
>>> -		(totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
>>> -		);
>>> -	}
>>> -
>>>  	/* zram devices sort of resembles non-rotational disks */
>>>  	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
>>> -
>>>  	zram->meta = meta;
>>>  	pr_debug("Initialization done!\n");
>>>  }
>>> @@ -771,14 +695,15 @@ static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
>>>  		disksize_show, disksize_store);
>>>  static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
>>>  static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
>>> -static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
>>> -static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);
>>> -static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
>>> -static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
>>> -static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
>>> -static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
>>> -static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
>>> -static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
>>> +static DEVICE_ATTR(memory_used, S_IRUGO, memory_used_show, NULL);
>>> +
>>> +ZRAM_ATTR_RO(num_reads);
>>> +ZRAM_ATTR_RO(num_writes);
>>> +ZRAM_ATTR_RO(pages_stored);
>>> +ZRAM_ATTR_RO(invalid_io);
>>> +ZRAM_ATTR_RO(notify_free);
>>> +ZRAM_ATTR_RO(pages_zero);
>>> +ZRAM_ATTR_RO(compressed_size);
>>>  
>>>  static struct attribute *zram_disk_attrs[] = {
>>>  	&dev_attr_disksize.attr,
>>> @@ -786,12 +711,12 @@ static struct attribute *zram_disk_attrs[] = {
>>>  	&dev_attr_reset.attr,
>>>  	&dev_attr_num_reads.attr,
>>>  	&dev_attr_num_writes.attr,
>>> +	&dev_attr_pages_stored.attr,
>>>  	&dev_attr_invalid_io.attr,
>>>  	&dev_attr_notify_free.attr,
>>> -	&dev_attr_zero_pages.attr,
>>> -	&dev_attr_orig_data_size.attr,
>>> -	&dev_attr_compr_data_size.attr,
>>> -	&dev_attr_mem_used_total.attr,
>>> +	&dev_attr_pages_zero.attr,
>>> +	&dev_attr_compressed_size.attr,
>>> +	&dev_attr_memory_used.attr,
>>>  	NULL,
>>>  };
>>>  
>>> diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
>>> index e81e9cd..277023d 100644
>>> --- a/drivers/block/zram/zram_drv.h
>>> +++ b/drivers/block/zram/zram_drv.h
>>> @@ -64,22 +64,19 @@ enum zram_pageflags {
>>>  struct table {
>>>  	unsigned long handle;
>>>  	u16 size;	/* object size (excluding header) */
>>> -	u8 count;	/* object ref count (not yet used) */
>>> -	u8 flags;
>>> +	u16 flags;
>>>  } __aligned(4);
>>>  
>>>  struct zram_stats {
>>> -	atomic64_t compr_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 num_writes;	/* number of writes */
>>> +	atomic64_t num_reads;	/* number of reads */
>>> +	atomic64_t pages_stored;	/* no. of pages currently stored */
>>> +	atomic64_t compressed_size;	/* compressed size of pages stored */
>>> +	atomic64_t pages_zero;		/* no. of zero filled pages */
>>> +	atomic64_t failed_reads;	/* no. of failed reads */
>>>  	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 */
>>> -	atomic_t good_compress;	/* % of pages with compression ratio<=50% */
>>> -	atomic_t bad_compress;	/* % of pages with compression ratio>=75% */
>>>  };
>>>  
>>>  struct zram_meta {
>>> -- 
>>> 1.8.5.3.493.gb139ac2
>>>
>>> --
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>>
>> -- 
>> Kind regards,
>> Minchan Kim
>>

Re: [PATCHv2 4/4] zram: report failed read and writes stats

[Jerome Marchand]

On 01/16/2014 01:58 AM, Minchan Kim wrote:
> On Wed, Jan 15, 2014 at 01:16:17PM +0300, Sergey Senozhatsky wrote:
>> zram accounted but did not report numbers of failed read
>> and write queries. make these stats available as failed_reads
>> and failed_writes attrs.
>>
>> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> Acked-by: Minchan Kim <minchan@kernel.org>
> 

This of course depends on third patch, but since I have no objection
to the ZRAM_ATTR_RO() macro part:

Acked-by: Jerome Marchand <jmarchan@redhat.com>