Commit 005411ea authored by Joe Lawrence's avatar Joe Lawrence Committed by Jens Axboe

doc: update block/queue-sysfs.txt entries

Add descriptions for dax, io_poll, and write_same_max_bytes files.
Signed-off-by: default avatarJoe Lawrence <>
Signed-off-by: default avatarJens Axboe <>
parent c21377f8
......@@ -14,6 +14,12 @@ add_random (RW)
This file allows to turn off the disk entropy contribution. Default
value of this file is '1'(on).
dax (RO)
This file indicates whether the device supports Direct Access (DAX),
used by CPU-addressable storage to bypass the pagecache. It shows '1'
if true, '0' if not.
discard_granularity (RO)
This shows the size of internal allocation of the device in bytes, if
......@@ -46,6 +52,12 @@ hw_sector_size (RO)
This is the hardware sector size of the device, in bytes.
io_poll (RW)
When read, this file shows the total number of block IO polls and how
many returned success. Writing '0' to this file will disable polling
for this device. Writing any non-zero value will enable this feature.
iostats (RW)
This file is used to control (on/off) the iostats accounting of the
......@@ -151,5 +163,11 @@ device state. This means that it might not be safe to toggle the
setting from "write back" to "write through", since that will also
eliminate cache flushes issued by the kernel.
write_same_max_bytes (RO)
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
Jens Axboe <>, February 2009
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