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