--- /dev/null
+/*
+ * 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;
+}