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120 lines
3.2 KiB
120 lines
3.2 KiB
/*
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* LLCStat Show LLC hit ratio for each process on each CPU core.
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* For Linux, uses BCC, eBPF. Embedded C.
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*
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* Basic example of BCC timed sampling perf event.
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*
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* USAGE: LLCStat [duration]
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*
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* Copyright (c) Facebook, Inc.
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* Licensed under the Apache License, Version 2.0 (the "License")
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*/
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#include <linux/perf_event.h>
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#include <unistd.h>
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#include <iomanip>
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#include <iostream>
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#include <string>
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#include "BPF.h"
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const std::string BPF_PROGRAM = R"(
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#include <linux/ptrace.h>
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#include <uapi/linux/bpf_perf_event.h>
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struct event_t {
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int cpu;
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int pid;
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char name[16];
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};
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BPF_HASH(ref_count, struct event_t);
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BPF_HASH(miss_count, struct event_t);
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static inline __attribute__((always_inline)) void get_key(struct event_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 event_t key = {};
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get_key(&key);
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u64 zero = 0, *val;
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val = miss_count.lookup_or_init(&key, &zero);
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(*val) += 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 event_t key = {};
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get_key(&key);
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u64 zero = 0, *val;
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val = ref_count.lookup_or_init(&key, &zero);
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(*val) += ctx->sample_period;
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return 0;
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}
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)";
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struct event_t {
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int cpu;
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int pid;
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char name[16];
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};
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int main(int argc, char** argv) {
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ebpf::BPF bpf;
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auto init_res = bpf.init(BPF_PROGRAM);
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if (init_res.code() != 0) {
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std::cerr << init_res.msg() << std::endl;
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return 1;
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}
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auto attach_ref_res =
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bpf.attach_perf_event(PERF_TYPE_HARDWARE, PERF_COUNT_HW_CACHE_REFERENCES,
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"on_cache_ref", 100, 0);
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if (attach_ref_res.code() != 0) {
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std::cerr << attach_ref_res.msg() << std::endl;
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return 1;
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}
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auto attach_miss_res = bpf.attach_perf_event(
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PERF_TYPE_HARDWARE, PERF_COUNT_HW_CACHE_MISSES, "on_cache_miss", 100, 0);
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if (attach_miss_res.code() != 0) {
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std::cerr << attach_miss_res.msg() << std::endl;
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return 1;
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}
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int probe_time = 10;
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if (argc == 2) {
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probe_time = atoi(argv[1]);
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}
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std::cout << "Probing for " << probe_time << " seconds" << std::endl;
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sleep(probe_time);
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bpf.detach_perf_event(PERF_TYPE_HARDWARE, PERF_COUNT_HW_CACHE_REFERENCES);
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bpf.detach_perf_event(PERF_TYPE_HARDWARE, PERF_COUNT_HW_CACHE_MISSES);
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auto refs = bpf.get_hash_table<event_t, uint64_t>("ref_count");
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auto misses = bpf.get_hash_table<event_t, uint64_t>("miss_count");
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for (auto it : refs.get_table_offline()) {
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uint64_t hit;
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try {
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auto miss = misses[it.first];
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hit = miss <= it.second ? it.second - miss : 0;
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} catch (...) {
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hit = it.second;
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}
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double ratio = (double(hit) / double(it.second)) * 100.0;
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std::cout << "PID " << std::setw(8) << std::setfill(' ') << it.first.pid;
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std::cout << std::setw(20) << std::setfill(' ') << std::left
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<< " (" + std::string(it.first.name) + ") " << std::right;
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std::cout << "on CPU " << std::setw(2) << std::setfill(' ') << it.first.cpu;
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std::cout << " Hit Rate " << std::setprecision(4) << ratio << "% ";
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std::cout << "(" << hit << "/" << it.second << ")" << std::endl;
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}
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return 0;
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}
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