+ <number_of_optional_arguments>
+ The number of optional arguments
+
+ <optional_arguments>
+ The following optional arguments are supported
+ precise_timestamps - use precise timer with nanosecond resolution
+ instead of the "jiffies" variable. When this argument is
+ used, the resulting times are in nanoseconds instead of
+ milliseconds. Precise timestamps are a little bit slower
+ to obtain than jiffies-based timestamps.
+ histogram:n1,n2,n3,n4,... - collect histogram of latencies. The
+ numbers n1, n2, etc are times that represent the boundaries
+ of the histogram. If precise_timestamps is not used, the
+ times are in milliseconds, otherwise they are in
+ nanoseconds. For each range, the kernel will report the
+ number of requests that completed within this range. For
+ example, if we use "histogram:10,20,30", the kernel will
+ report four numbers a:b:c:d. a is the number of requests
+ that took 0-10 ms to complete, b is the number of requests
+ that took 10-20 ms to complete, c is the number of requests
+ that took 20-30 ms to complete and d is the number of
+ requests that took more than 30 ms to complete.
+