diff options
Diffstat (limited to 'Documentation/block/queue-sysfs.txt')
| -rw-r--r-- | Documentation/block/queue-sysfs.txt | 64 |
1 files changed, 43 insertions, 21 deletions
diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt index 83b457e24bbae..b40b5b7cebd95 100644 --- a/Documentation/block/queue-sysfs.txt +++ b/Documentation/block/queue-sysfs.txt @@ -14,6 +14,15 @@ add_random (RW) This file allows to turn off the disk entropy contribution. Default value of this file is '1'(on). +chunk_sectors (RO) +------------------ +This has different meaning depending on the type of the block device. +For a RAID device (dm-raid), chunk_sectors indicates the size in 512B sectors +of the RAID volume stripe segment. For a zoned block device, either host-aware +or host-managed, chunk_sectors indicates the size in 512B sectors of the zones +of the device, with the eventual exception of the last zone of the device which +may be smaller. + dax (RO) -------- This file indicates whether the device supports Direct Access (DAX), @@ -43,6 +52,16 @@ large discards are issued, setting this value lower will make Linux issue smaller discards and potentially help reduce latencies induced by large discard operations. +discard_zeroes_data (RO) +------------------------ +Obsolete. Always zero. + +fua (RO) +-------- +Whether or not the block driver supports the FUA flag for write requests. +FUA stands for Force Unit Access. If the FUA flag is set that means that +write requests must bypass the volatile cache of the storage device. + hw_sector_size (RO) ------------------- This is the hardware sector size of the device, in bytes. @@ -83,14 +102,19 @@ logical_block_size (RO) ----------------------- This is the logical block size of the device, in bytes. +max_discard_segments (RO) +------------------------- +The maximum number of DMA scatter/gather entries in a discard request. + max_hw_sectors_kb (RO) ---------------------- This is the maximum number of kilobytes supported in a single data transfer. max_integrity_segments (RO) --------------------------- -When read, this file shows the max limit of integrity segments as -set by block layer which a hardware controller can handle. +Maximum number of elements in a DMA scatter/gather list with integrity +data that will be submitted by the block layer core to the associated +block driver. max_sectors_kb (RW) ------------------- @@ -100,11 +124,12 @@ size allowed by the hardware. max_segments (RO) ----------------- -Maximum number of segments of the device. +Maximum number of elements in a DMA scatter/gather list that is submitted +to the associated block driver. max_segment_size (RO) --------------------- -Maximum segment size of the device. +Maximum size in bytes of a single element in a DMA scatter/gather list. minimum_io_size (RO) -------------------- @@ -132,6 +157,12 @@ per-block-cgroup request pool. IOW, if there are N block cgroups, each request queue may have up to N request pools, each independently regulated by nr_requests. +nr_zones (RO) +------------- +For zoned block devices (zoned attribute indicating "host-managed" or +"host-aware"), this indicates the total number of zones of the device. +This is always 0 for regular block devices. + optimal_io_size (RO) -------------------- This is the optimal IO size reported by the device. @@ -185,8 +216,8 @@ This is the number of bytes the device can write in a single write-same command. A value of '0' means write-same is not supported by this device. -wb_lat_usec (RW) ----------------- +wbt_lat_usec (RW) +----------------- If the device is registered for writeback throttling, then this file shows the target minimum read latency. If this latency is exceeded in a given window of time (see wb_window_usec), then the writeback throttling will start @@ -201,6 +232,12 @@ blk-throttle makes decision based on the samplings. Lower time means cgroups have more smooth throughput, but higher CPU overhead. This exists only when CONFIG_BLK_DEV_THROTTLING_LOW is enabled. +write_zeroes_max_bytes (RO) +--------------------------- +For block drivers that support REQ_OP_WRITE_ZEROES, the maximum number of +bytes that can be zeroed at once. The value 0 means that REQ_OP_WRITE_ZEROES +is not supported. + zoned (RO) ---------- This indicates if the device is a zoned block device and the zone model of the @@ -213,19 +250,4 @@ devices are described in the ZBC (Zoned Block Commands) and ZAC do not support zone commands, they will be treated as regular block devices and zoned will report "none". -nr_zones (RO) -------------- -For zoned block devices (zoned attribute indicating "host-managed" or -"host-aware"), this indicates the total number of zones of the device. -This is always 0 for regular block devices. - -chunk_sectors (RO) ------------------- -This has different meaning depending on the type of the block device. -For a RAID device (dm-raid), chunk_sectors indicates the size in 512B sectors -of the RAID volume stripe segment. For a zoned block device, either host-aware -or host-managed, chunk_sectors indicates the size in 512B sectors of the zones -of the device, with the eventual exception of the last zone of the device which -may be smaller. - Jens Axboe <jens.axboe@oracle.com>, February 2009 |