llcstat - Summarize CPU cache references and misses by process. Uses Linux
llcstat [-h] [-c SAMPLE_PERIOD] [duration]
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
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
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.
CONFIG_BPF and bcc.
- Print usage message.
- -c SAMPLE_PERIOD
- Sample one in this many cache reference and cache miss
- Duration to trace, in seconds.
- Sample one in 100 events, trace for 20 seconds:
- # llcstat -c 100 20
- Process ID
- Process name
- CPU ID
- Number of cache reference events
- Number of cache miss events
- Cache hit ratio
This is from bcc.
Also look in the bcc distribution for a companion _examples.txt file containing
example usage, output, and commentary for this tool.
Unstable - in development.