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