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authorDapeng Mi <dapeng1.mi@linux.intel.com>2026-09-17 09:52:33 +0800
committerIngo Molnar <mingo@kernel.org>2026-09-22 11:37:46 +0200
commit0102c8c7fdfc4bd700971daff2b94470f4eafae4 (patch)
tree531306c2299f9a269f0a986e29f17ba972180104 /Documentation/ABI/testing/sysfs-block-zram
downloadlinux-stable-0102c8c7fdfc4bd700971daff2b94470f4eafae4.tar.gz
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perf/x86/intel: Rename DMR offcore_rsp attribute to offmodule_rspgrafted
DMR introduces Offmodule Response events in place of the legacy Offcore Response events, but it still exposes the inherited offcore_rsp PMU attribute for programming the corresponding MSR data. Rename the DMR PMU attribute to offmodule_rsp so the sysfs interface matches the underlying event name and avoids user & tooling confusion. Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://patch.msgid.link/20260917015234.981153-12-dapeng1.mi@linux.intel.com
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+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>/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>/mem_used_max
+Date: August 2014
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ The mem_used_max file is write-only and is used to reset
+ the counter 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 write-only 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.
+
+What: /sys/block/zram<id>/backing_dev
+Date: June 2017
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ The backing_dev file is read-write and set up backing
+ device for zram to write incompressible pages.
+ For using, user should enable CONFIG_ZRAM_WRITEBACK.
+
+What: /sys/block/zram<id>/idle
+Date: November 2018
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ idle file is write-only and mark zram slot as idle.
+ If system has mounted debugfs, user can see which slots
+ are idle via /sys/kernel/debug/zram/zram<id>/block_state
+
+What: /sys/block/zram<id>/writeback
+Date: November 2018
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ The writeback file is write-only and trigger idle and/or
+ huge page writeback to backing device.
+
+What: /sys/block/zram<id>/bd_stat
+Date: November 2018
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ The bd_stat file is read-only and represents backing device's
+ statistics (bd_count, bd_reads, bd_writes) in a format
+ similar to block layer statistics file format.
+
+What: /sys/block/zram<id>/writeback_limit_enable
+Date: November 2018
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ The writeback_limit_enable file is read-write and specifies
+ eanbe of writeback_limit feature. "1" means eable the feature.
+ No limit "0" is the initial state.
+
+What: /sys/block/zram<id>/writeback_limit
+Date: November 2018
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ The writeback_limit file is read-write and specifies the maximum
+ amount of writeback ZRAM can do. The limit could be changed
+ in run time.
+
+What: /sys/block/zram<id>/recomp_algorithm
+Date: November 2022
+Contact: Sergey Senozhatsky <senozhatsky@chromium.org>
+Description:
+ The recomp_algorithm file is read-write and allows to set
+ or show secondary compression algorithms.
+
+What: /sys/block/zram<id>/recompress
+Date: November 2022
+Contact: Sergey Senozhatsky <senozhatsky@chromium.org>
+Description:
+ The recompress file is write-only and triggers re-compression
+ with secondary compression algorithms.
+
+What: /sys/block/zram<id>/algorithm_params
+Date: August 2024
+Contact: Sergey Senozhatsky <senozhatsky@chromium.org>
+Description:
+ The algorithm_params file is write-only and is used to setup
+ compression algorithm parameters.
+
+What: /sys/block/zram<id>/compressed_writeback
+Date: December 2025
+Contact: Richard Chang <richardycc@google.com>
+Description:
+ The compressed_writeback device attribute toggles compressed
+ writeback feature.
+
+What: /sys/block/zram<id>/writeback_batch_size
+Date: November 2025
+Contact: Sergey Senozhatsky <senozhatsky@chromium.org>
+Description:
+ The writeback_batch_size device attribute sets the maximum
+ number of in-flight writeback operations.