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-rw-r--r--Documentation/block/queue-sysfs.txt6
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