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120 lines
3.6 KiB
120 lines
3.6 KiB
#!/usr/bin/env python
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#
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# llcstat.py Summarize cache references and cache misses by PID.
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# Cache reference and cache miss are corresponding events defined in
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# uapi/linux/perf_event.h, it varies to different architecture.
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# On x86-64, they mean LLC references and LLC misses.
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#
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# For Linux, uses BCC, eBPF. Embedded C.
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#
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# SEE ALSO: perf top -e cache-misses -e cache-references -a -ns pid,cpu,comm
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#
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# REQUIRES: Linux 4.9+ (BPF_PROG_TYPE_PERF_EVENT support).
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#
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# Copyright (c) 2016 Facebook, Inc.
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# Licensed under the Apache License, Version 2.0 (the "License")
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#
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# 19-Oct-2016 Teng Qin Created this.
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from __future__ import print_function
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import argparse
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from bcc import BPF, PerfType, PerfHWConfig
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import signal
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from time import sleep
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parser = argparse.ArgumentParser(
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description="Summarize cache references and misses by PID",
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formatter_class=argparse.RawDescriptionHelpFormatter)
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parser.add_argument(
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"-c", "--sample_period", type=int, default=100,
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help="Sample one in this many number of cache reference / miss events")
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parser.add_argument(
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"duration", nargs="?", default=10, help="Duration, in seconds, to run")
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parser.add_argument("--ebpf", action="store_true",
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help=argparse.SUPPRESS)
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args = parser.parse_args()
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# load BPF program
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bpf_text="""
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#include <linux/ptrace.h>
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#include <uapi/linux/bpf_perf_event.h>
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struct key_t {
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int cpu;
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int pid;
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char name[TASK_COMM_LEN];
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};
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BPF_HASH(ref_count, struct key_t);
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BPF_HASH(miss_count, struct key_t);
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static inline __attribute__((always_inline)) void get_key(struct key_t* key) {
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key->cpu = bpf_get_smp_processor_id();
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key->pid = bpf_get_current_pid_tgid();
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bpf_get_current_comm(&(key->name), sizeof(key->name));
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}
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int on_cache_miss(struct bpf_perf_event_data *ctx) {
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struct key_t key = {};
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get_key(&key);
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miss_count.increment(key, ctx->sample_period);
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return 0;
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}
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int on_cache_ref(struct bpf_perf_event_data *ctx) {
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struct key_t key = {};
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get_key(&key);
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ref_count.increment(key, ctx->sample_period);
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return 0;
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}
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"""
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if args.ebpf:
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print(bpf_text)
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exit()
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b = BPF(text=bpf_text)
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try:
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b.attach_perf_event(
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ev_type=PerfType.HARDWARE, ev_config=PerfHWConfig.CACHE_MISSES,
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fn_name="on_cache_miss", sample_period=args.sample_period)
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b.attach_perf_event(
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ev_type=PerfType.HARDWARE, ev_config=PerfHWConfig.CACHE_REFERENCES,
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fn_name="on_cache_ref", sample_period=args.sample_period)
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except Exception:
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print("Failed to attach to a hardware event. Is this a virtual machine?")
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exit()
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print("Running for {} seconds or hit Ctrl-C to end.".format(args.duration))
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try:
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sleep(float(args.duration))
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except KeyboardInterrupt:
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signal.signal(signal.SIGINT, lambda signal, frame: print())
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miss_count = {}
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for (k, v) in b.get_table('miss_count').items():
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miss_count[(k.pid, k.cpu, k.name)] = v.value
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print('PID NAME CPU REFERENCE MISS HIT%')
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tot_ref = 0
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tot_miss = 0
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for (k, v) in b.get_table('ref_count').items():
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try:
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miss = miss_count[(k.pid, k.cpu, k.name)]
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except KeyError:
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miss = 0
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tot_ref += v.value
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tot_miss += miss
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# This happens on some PIDs due to missed counts caused by sampling
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hit = (v.value - miss) if (v.value >= miss) else 0
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print('{:<8d} {:<16s} {:<4d} {:>12d} {:>12d} {:>6.2f}%'.format(
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k.pid, k.name.decode('utf-8', 'replace'), k.cpu, v.value, miss,
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(float(hit) / float(v.value)) * 100.0))
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print('Total References: {} Total Misses: {} Hit Rate: {:.2f}%'.format(
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tot_ref, tot_miss, (float(tot_ref - tot_miss) / float(tot_ref)) * 100.0))
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