Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdim...

[mirror_ubuntu-zesty-kernel.git] / Documentation / ABI / testing / sysfs-block-zram

What:		/sys/block/zram<id>/disksize
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The disksize file is read-write and specifies the disk size
		which represents the limit on the *uncompressed* worth of data
		that can be stored in this disk.
		Unit: bytes

What:		/sys/block/zram<id>/initstate
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The initstate file is read-only and shows the initialization
		state of the device.

What:		/sys/block/zram<id>/reset
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The reset file is write-only and allows resetting the
		device. The reset operation frees all the memory associated
		with this device.

What:		/sys/block/zram<id>/num_reads
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The num_reads file is read-only and specifies the number of
		reads (failed or successful) done on this device.

What:		/sys/block/zram<id>/num_writes
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The num_writes file is read-only and specifies the number of
		writes (failed or successful) done on this device.

What:		/sys/block/zram<id>/invalid_io
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The invalid_io file is read-only and specifies the number of
		non-page-size-aligned I/O requests issued to this device.

What:		/sys/block/zram<id>/failed_reads
Date:		February 2014
Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Description:
		The failed_reads file is read-only and specifies the number of
		failed reads happened on this device.

What:		/sys/block/zram<id>/failed_writes
Date:		February 2014
Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Description:
		The failed_writes file is read-only and specifies the number of
		failed writes happened on this device.

What:		/sys/block/zram<id>/max_comp_streams
Date:		February 2014
Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Description:
		The max_comp_streams file is read-write and specifies the
		number of backend's zcomp_strm compression streams (number of
		concurrent compress operations).

What:		/sys/block/zram<id>/comp_algorithm
Date:		February 2014
Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Description:
		The comp_algorithm file is read-write and lets to show
		available and selected compression algorithms, change
		compression algorithm selection.

What:		/sys/block/zram<id>/notify_free
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The notify_free file is read-only. Depending on device usage
		scenario it may account a) the number of pages freed because
		of swap slot free notifications or b) the number of pages freed
		because of REQ_DISCARD requests sent by bio. The former ones
		are sent to a swap block device when a swap slot is freed, which
		implies that this disk is being used as a swap disk. The latter
		ones are sent by filesystem mounted with discard option,
		whenever some data blocks are getting discarded.

What:		/sys/block/zram<id>/zero_pages
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The zero_pages file is read-only and specifies number of zero
		filled pages written to this disk. No memory is allocated for
		such pages.

What:		/sys/block/zram<id>/orig_data_size
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The orig_data_size file is read-only and specifies uncompressed
		size of data stored in this disk. This excludes zero-filled
		pages (zero_pages) since no memory is allocated for them.
		Unit: bytes

What:		/sys/block/zram<id>/compr_data_size
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The compr_data_size file is read-only and specifies compressed
		size of data stored in this disk. So, compression ratio can be
		calculated using orig_data_size and this statistic.
		Unit: bytes

What:		/sys/block/zram<id>/mem_used_total
Date:		August 2010
Contact:	Nitin Gupta <ngupta@vflare.org>
Description:
		The mem_used_total file is read-only and specifies the amount
		of memory, including allocator fragmentation and metadata
		overhead, allocated for this disk. So, allocator space
		efficiency can be calculated using compr_data_size and this
		statistic.
		Unit: bytes

What:		/sys/block/zram<id>/mem_used_max
Date:		August 2014
Contact:	Minchan Kim <minchan@kernel.org>
Description:
		The mem_used_max file is read/write and specifies the amount
		of maximum memory zram have consumed to store compressed data.
		For resetting the value, you should write "0". Otherwise,
		you could see -EINVAL.
		Unit: bytes

What:		/sys/block/zram<id>/mem_limit
Date:		August 2014
Contact:	Minchan Kim <minchan@kernel.org>
Description:
		The mem_limit file is read/write and specifies the maximum
		amount of memory ZRAM can use to store the compressed data.  The
		limit could be changed in run time and "0" means disable the
		limit.  No limit is the initial state.  Unit: bytes

What:		/sys/block/zram<id>/compact
Date:		August 2015
Contact:	Minchan Kim <minchan@kernel.org>
Description:
		The compact file is write-only and trigger compaction for
		allocator zrm uses. The allocator moves some objects so that
		it could free fragment space.

What:		/sys/block/zram<id>/io_stat
Date:		August 2015
Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Description:
		The io_stat file is read-only and accumulates device's I/O
		statistics not accounted by block layer. For example,
		failed_reads, failed_writes, etc. File format is similar to
		block layer statistics file format.

What:		/sys/block/zram<id>/mm_stat
Date:		August 2015
Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
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.