From fbbe7c86b483878da4a2ec7b899e0814195942af Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Fri, 28 Jun 2019 13:07:45 -0700 Subject: [PATCH] block, documentation: Document discard_zeroes_data, fua, max_discard_segments and write_zeroes_max_bytes Reviewed-by: Martin K. Petersen Signed-off-by: Bart Van Assche Signed-off-by: Jens Axboe --- Documentation/block/queue-sysfs.txt | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt index 1515dcf3dec4..b40b5b7cebd9 100644 --- a/Documentation/block/queue-sysfs.txt +++ b/Documentation/block/queue-sysfs.txt @@ -52,6 +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. @@ -92,6 +102,10 @@ 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. @@ -218,6 +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 -- 2.30.2