Manual: runqlen-bpfcc

runqlen(8)					   System Manager's Manual					  runqlen(8)

NAME
       runqlen - Scheduler run queue length as a histogram.

SYNOPSIS
       runqlen [-h] [-T] [-O] [-C] [interval] [count]

DESCRIPTION
       This  program  summarizes  scheduler  queue length as a histogram, and can also show run queue occupancy. It works by
       sampling the run queue length on all CPUs at 99 Hertz.

       This tool can be used to identify imbalances, eg, when processes are bound to CPUs  causing  queueing,  or  interrupt
       mappings causing the same.

       Since this uses BPF, only the root user can use this tool.

REQUIREMENTS
       CONFIG_BPF and bcc.

OPTIONS
       -h     Print usage message.

       -T     Include timestamps on output.

       -O     Report run queue occupancy.

       -C     Report for each CPU.

       interval
	      Output interval, in seconds.

       count  Number of outputs.

EXAMPLES
       Summarize run queue length as a histogram:
	      # runqlen

       Print 1 second summaries, 10 times:
	      # runqlen 1 10

       Print output every second, with timestamps, and show each CPU separately:
	      # runqlen -CT 1

       Print run queue occupancy every second:
	      # runqlen -O 1

       Print run queue occupancy, with timestamps, for each CPU:
	      # runqlen -COT 1

FIELDS
       runqlen
	      Scheduler	 run  queue length: the number of threads (tasks) waiting to run, (excluding including the currently
	      running task).

       count  Number of samples at this queue length.

       distribution
	      An ASCII bar chart to visualize the distribution (count column)

OVERHEAD
       This uses sampling at 99 Hertz (on all CPUs), and in-kernel summaries, which should make	 overhead  negligible.	This
       does not trace scheduler events, like runqlen does, which comes at a much higher overhead cost.

SOURCE
       This is from bcc.

	      https://github.com/iovisor/bcc

       Also look in the bcc distribution for a companion _examples.txt file containing example usage, output, and commentary
       for this tool.

OS
       Linux

STABILITY
       Unstable - in development.

AUTHOR
       Brendan Gregg

SEE ALSO
       runqlat(8), runqslower(8), pidstat(1)

USER COMMANDS						 2016-12-12						  runqlen(8)