Initializing Queue Statistics; Qs_Wait; Qs_Run; Qs_Done - Red Hat ENTERPRISE LINUX 5.4 - SYSTEMTAP LANGUAGE Reference Manual

Initializing queue statistics

user_string_quoted:string (addr:long)
This function copies a string from userspace at given address. Any ASCII characters that are not
printable are replaced by the corresponding escape sequence in the returned string.
9.5. Initializing queue statistics
The queue_stats tapset provides functions that, when given notification of queuing events like wait,
run, or done, track averages such as queue length, service and wait times, and utilization. Call the
following three functions from appropriate probes, in sequence.

9.5.1. qs_wait

General syntax:
qs_wait:unknown (qname:string)
This function records that a new request was enqueued for the given queue name.

9.5.2. qs_run

General syntax:
qs_run:unknown (qname:string)
This function records that a previously enqueued request was removed from the given wait queue and
is now being serviced.

9.5.3. qs_done

General syntax:
qs_done:unknown (qname:string)
This function records that a request originally from the given queue has completed being serviced.

9.6. Using queue statistics

Functions with the qsq_ prefix query the statistics averaged since the first queue operation or when
qsq_start was called. Since statistics are often fractional, a scale parameter multiplies the result to a
more useful scale. For some fractions, a scale of 100 returns percentage numbers.

9.6.1. qsq_blocked

General syntax:
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