linux.git/Documentation/block/queue-sysfs.txt, branch v5.1

block: add documentation for io_timeout

2019-01-05T02:19:51+00:00

Add documentation for /sys/block//queue/io_timeout.

Reviewed-by: Bart Van Assche 
Signed-off-by: Weiping Zhang 
Signed-off-by: Jens Axboe

block: update sysfs documentation

2018-12-17T02:53:06+00:00

Add the description of the zoned, nr_zones and chunk_sectors sysfs queue
attributes to Documentation/block/queue-sysfs.txt. The description of
the zoned and chunk_sector attributes are mostly copied from
ABI/testing/sysfs-block (added a typo fix). While at it, also fix a
typo in the description of the io_poll_delay attribute.

nr_zones description is also added to ABI/testing/sysfs-block and
contact email address updated for the zoned attribute.

Signed-off-by: Damien Le Moal 
Signed-off-by: Jens Axboe

block: remove the discard_zeroes_data flag

2017-04-08T17:25:38+00:00

Now that we use the proper REQ_OP_WRITE_ZEROES operation everywhere we can
kill this hack.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Hannes Reinecke 
Signed-off-by: Jens Axboe

blk-throttle: make throtl_slice tunable

2017-03-28T14:02:20+00:00

throtl_slice is important for blk-throttling. It's called slice
internally but it really is a time window blk-throttling samples data.
blk-throttling will make decision based on the samplings. An example is
bandwidth measurement. A cgroup's bandwidth is measured in the time
interval of throtl_slice.

A small throtl_slice meanse cgroups have smoother throughput but burn
more CPUs. It has 100ms default value, which is not appropriate for all
disks. A fast SSD can dispatch a lot of IOs in 100ms. This patch makes
it tunable.

Since throtl_slice isn't a time slice, the sysfs name
'throttle_sample_time' reflects its character better.

Signed-off-by: Shaohua Li 
Signed-off-by: Jens Axboe

block: fix up io_poll documentation

2017-01-03T23:47:13+00:00

/sys/block//queue/io_poll is a boolean.  Fix the docs.

Signed-off-by: Jeff Moyer 
Signed-off-by: Jens Axboe

blk-wbt: allow reset of default latency through sysfs

2016-11-28T17:27:03+00:00

Allow a write of '-1' to reset the default latency target for
a given device. This removes knowledge of the different default
settings for rotational vs non-rotational from user space.

Signed-off-by: Jens Axboe

block: document the 'io_poll_delay' queue sysfs file

2016-11-18T05:23:02+00:00

This was documented in the original commit, 64f1c21e86f7, but it
never made it into the proper location for queue sysfs files.

Signed-off-by: Jens Axboe

block: hook up writeback throttling

2016-11-10T20:53:40+00:00

Enable throttling of buffered writeback to make it a lot
more smooth, and has way less impact on other system activity.
Background writeback should be, by definition, background
activity. The fact that we flush huge bundles of it at the time
means that it potentially has heavy impacts on foreground workloads,
which isn't ideal. We can't easily limit the sizes of writes that
we do, since that would impact file system layout in the presence
of delayed allocation. So just throttle back buffered writeback,
unless someone is waiting for it.

The algorithm for when to throttle takes its inspiration in the
CoDel networking scheduling algorithm. Like CoDel, blk-wb monitors
the minimum latencies of requests over a window of time. In that
window of time, if the minimum latency of any request exceeds a
given target, then a scale count is incremented and the queue depth
is shrunk. The next monitoring window is shrunk accordingly. Unlike
CoDel, if we hit a window that exhibits good behavior, then we
simply increment the scale count and re-calculate the limits for that
scale value. This prevents us from oscillating between a
close-to-ideal value and max all the time, instead remaining in the
windows where we get good behavior.

Unlike CoDel, blk-wb allows the scale count to to negative. This
happens if we primarily have writes going on. Unlike positive
scale counts, this doesn't change the size of the monitoring window.
When the heavy writers finish, blk-bw quickly snaps back to it's
stable state of a zero scale count.

The patch registers a sysfs entry, 'wb_lat_usec'. This sets the latency
target to me met. It defaults to 2 msec for non-rotational storage, and
75 msec for rotational storage. Setting this value to '0' disables
blk-wb. Generally, a user would not have to touch this setting.

We don't enable WBT on devices that are managed with CFQ, and have
a non-root block cgroup attached. If we have a proportional share setup
on this particular disk, then the wbt throttling will interfere with
that. We don't have a strong need for wbt for that case, since we will
rely on CFQ doing that for us.

Signed-off-by: Jens Axboe

doc: update block/queue-sysfs.txt entries

2016-08-11T15:37:23+00:00

Add descriptions for dax, io_poll, and write_same_max_bytes files.

Signed-off-by: Joe Lawrence 
Signed-off-by: Jens Axboe

Doc: block: Fix a typo in queue-sysfs.txt

2016-06-28T20:14:16+00:00

This patch fix a spelling typo found in queue-sysfs.txt.

Signed-off-by: Masanari Iida 
Signed-off-by: Jens Axboe