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Commit 623e47fc authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Linus Torvalds
Browse files

zram: introduce per-device debug_stat sysfs node 

debug_stat sysfs is read-only and represents various debugging data that
zram developers may need.  This file is not meant to be used by anyone
else: its content is not documented and will change any time w/o any
notice.  Therefore, the output of debug_stat file contains a version
string.  To avoid any confusion, we will increase the version number
every time we modify the output.

At the moment this file exports only one value -- the number of
re-compressions, IOW, the number of times compression fast path has
failed.  This stat is temporary any will be useful in case if any
per-cpu compression streams regressions will be reported.

Link: http://lkml.kernel.org/r/20160513230834.GB26763@bbox
Link: http://lkml.kernel.org/r/20160511134553.12655-1-sergey.senozhatsky@gmail.com


Signed-off-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 43209ea2

Documentation/ABI/testing/sysfs-block-zram

+9 −0
Original line number Diff line number Diff line
@@ -166,3 +166,12 @@ Description: 
		The mm_stat file is read-only and represents device's mm

		statistics (orig_data_size, compr_data_size, etc.) in a format

		similar to block layer statistics file format.



What:		/sys/block/zram<id>/debug_stat

Date:		July 2016

Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

Description:

		The debug_stat file is read-only and represents various

		device's debugging info useful for kernel developers. Its

		format is not documented intentionally and may change

		anytime without any notice.

Documentation/blockdev/zram.txt

+1 −0
Original line number Diff line number Diff line
@@ -172,6 +172,7 @@ mem_limit RW the maximum amount of memory ZRAM can use to store 
pages_compacted   RO    the number of pages freed during compaction

                        (available only via zram<id>/mm_stat node)

compact           WO    trigger memory compaction

debug_stat        RO    this file is used for zram debugging purposes



WARNING

=======

drivers/block/zram/zram_drv.c

+21 −0
Original line number Diff line number Diff line
@@ -435,8 +435,26 @@ static ssize_t mm_stat_show(struct device *dev, 
	return ret;

}



static ssize_t debug_stat_show(struct device *dev,

		struct device_attribute *attr, char *buf)

{

	int version = 1;

	struct zram *zram = dev_to_zram(dev);

	ssize_t ret;



	down_read(&zram->init_lock);

	ret = scnprintf(buf, PAGE_SIZE,

			"version: %d\n%8llu\n",

			version,

			(u64)atomic64_read(&zram->stats.writestall));

	up_read(&zram->init_lock);



	return ret;

}



static DEVICE_ATTR_RO(io_stat);

static DEVICE_ATTR_RO(mm_stat);

static DEVICE_ATTR_RO(debug_stat);

ZRAM_ATTR_RO(num_reads);

ZRAM_ATTR_RO(num_writes);

ZRAM_ATTR_RO(failed_reads);
@@ -719,6 +737,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, 
		zcomp_strm_release(zram->comp, zstrm);

		zstrm = NULL;



		atomic64_inc(&zram->stats.writestall);



		handle = zs_malloc(meta->mem_pool, clen,

				GFP_NOIO | __GFP_HIGHMEM);

		if (handle)
@@ -1181,6 +1201,7 @@ static struct attribute *zram_disk_attrs[] = { 
	&dev_attr_comp_algorithm.attr,

	&dev_attr_io_stat.attr,

	&dev_attr_mm_stat.attr,

	&dev_attr_debug_stat.attr,

	NULL,

};

drivers/block/zram/zram_drv.h

+1 −0
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ struct zram_stats { 
	atomic64_t zero_pages;		/* no. of zero filled pages */

	atomic64_t pages_stored;	/* no. of pages currently stored */

	atomic_long_t max_used_pages;	/* no. of maximum pages stored */

	atomic64_t writestall;		/* no. of write slow paths */

};



struct zram_meta {