1llcstat(8) System Manager's Manual llcstat(8)
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6 llcstat - Summarize CPU cache references and misses by process. Uses
7 Linux eBPF/bcc.
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10 llcstat [-h] [-c SAMPLE_PERIOD] [duration]
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13 llcstat instruments CPU cache references and cache misses system-side,
14 and summarizes them by PID and CPU. These events have different mean‐
15 ings on different architecture. For x86-64, they mean misses and refer‐
16 ences to LLC. This can be useful to locate and debug performance is‐
17 sues caused by cache hit rate.
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19 This works by sampling corresponding events defined in
20 uapi/linux/perf_event.h, namely PERF_COUNT_HW_CACHE_REFERENCES and
21 PERF_COUNT_HW_CACHE_MISSES, using BPF perf event tracing. Upon each
22 sampled event, the attached BPF program records the PID and CPU ID on
23 which the event happened, and stores it in table.
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25 This makes use of a Linux 4.9 feature (BPF_PROG_TYPE_PERF_EVENT).
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27 Since this uses BPF, only the root user can use this tool.
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30 CONFIG_BPF and bcc.
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33 -h Print usage message.
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35 -c SAMPLE_PERIOD
36 Sample one in this many cache reference and cache miss events.
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38 -t Summarize cache references and misses by PID/TID
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40 duration
41 Duration to trace, in seconds.
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44 Sample one in 100 events, trace for 20 seconds:
45 # llcstat -c 100 20
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48 PID Process ID
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50 NAME Process name
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52 CPU CPU ID
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54 REFERENCE
55 Number of cache reference events
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57 MISS Number of cache miss events
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59 HIT% Cache hit ratio
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62 This is from bcc.
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64 https://github.com/iovisor/bcc
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66 Also look in the bcc distribution for a companion _examples.txt file
67 containing example usage, output, and commentary for this tool.
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70 Linux
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73 Unstable - in development.
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76 Teng Qin
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79 Perf can be used as a generic event counter tool. An example for LLC:
80 # perf top -e cache-misses -e cache-references -a -ns
81 pid,cpu,comm
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85USER COMMANDS 2015-08-18 llcstat(8)