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| author | Shaohua Li <shli@fb.com> | 2017-03-27 10:51:37 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-03-28 08:02:20 -0600 |
| commit | 297e3d854784821d3b8ff3ae117f20d71f125504 (patch) | |
| tree | 1909a3ce719f5a434d4e4e7584424b3559738be0 /Documentation/block | |
| parent | 06cceedcca67a93ac7f7aa93bbd9980c7496d14e (diff) | |
| download | lwn-297e3d854784821d3b8ff3ae117f20d71f125504.tar.gz lwn-297e3d854784821d3b8ff3ae117f20d71f125504.zip | |
blk-throttle: make throtl_slice tunable
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 <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'Documentation/block')
| -rw-r--r-- | Documentation/block/queue-sysfs.txt | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt index c0a3bb5a6e4e..b7f6bdc96d73 100644 --- a/Documentation/block/queue-sysfs.txt +++ b/Documentation/block/queue-sysfs.txt @@ -192,5 +192,11 @@ scaling back writes. Writing a value of '0' to this file disables the feature. Writing a value of '-1' to this file resets the value to the default setting. +throttle_sample_time (RW) +------------------------- +This is the time window that blk-throttle samples data, in millisecond. +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. Jens Axboe <jens.axboe@oracle.com>, February 2009 |