Manual: llcstat-bpfcc

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

NAME
       llcstat - Summarize CPU cache references and misses by process. Uses Linux eBPF/bcc.

SYNOPSIS
       llcstat [-h] [-c SAMPLE_PERIOD] [duration]

DESCRIPTION
       llcstat	instruments  CPU  cache	 references  and cache misses system-side, and summarizes them by PID and CPU. These
       events have different meanings on different architecture. For x86-64, they mean misses and references to	 LLC.	This
       can be useful to locate and debug performance issues caused by cache hit rate.

       This works by sampling corresponding events defined in uapi/linux/perf_event.h, namely PERF_COUNT_HW_CACHE_REFERENCES
       and  PERF_COUNT_HW_CACHE_MISSES,	 using	BPF  perf  event  tracing. Upon each sampled event, the attached BPF program
       records the PID and CPU ID on which the event happened, and stores it in table.

       This makes use of a Linux 4.9 feature (BPF_PROG_TYPE_PERF_EVENT).

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

REQUIREMENTS
       CONFIG_BPF and bcc.

OPTIONS
       -h     Print usage message.

       -c SAMPLE_PERIOD
	      Sample one in this many cache reference and cache miss events.

       -t     Summarize cache references and misses by PID/TID

       duration
	      Duration to trace, in seconds.

EXAMPLES
       Sample one in 100 events, trace for 20 seconds:
	      # llcstat -c 100 20

FIELDS
       PID    Process ID

       NAME   Process name

       CPU    CPU ID

       REFERENCE
	      Number of cache reference events

       MISS   Number of cache miss events

       HIT%   Cache hit ratio

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
       Teng Qin

SEE ALSO
       Perf can be used as a generic event counter tool. An example for LLC:
	      # perf top -e cache-misses -e cache-references -a -ns pid,cpu,comm

USER COMMANDS						 2015-08-18						  llcstat(8)