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)