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Copy pathFollyRequestContextSwitch.cc
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105 lines (86 loc) · 2.54 KB
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/*
* FollyRequestContextSwitch Monitor RequestContext switch events for any binary
* uses the class from [folly](http://bit.ly/2h6S1yx).
* For Linux, uses BCC, eBPF. Embedded C.
*
* Basic example of using USDT with BCC.
*
* USAGE: FollyRequestContextSwitch PATH_TO_BINARY
*
* Copyright (c) Facebook, Inc.
* Licensed under the Apache License, Version 2.0 (the "License")
*/
#include <signal.h>
#include <iostream>
#include <vector>
#include "BPF.h"
const std::string BPF_PROGRAM = R"(
#include <linux/sched.h>
#include <uapi/linux/ptrace.h>
struct event_t {
int pid;
char name[16];
uint64_t old_addr;
uint64_t new_addr;
};
BPF_PERF_OUTPUT(events);
int on_context_switch(struct pt_regs *ctx) {
struct event_t event = {};
event.pid = bpf_get_current_pid_tgid();
bpf_get_current_comm(&event.name, sizeof(event.name));
bpf_usdt_readarg(1, ctx, &event.old_addr);
bpf_usdt_readarg(2, ctx, &event.new_addr);
events.perf_submit(ctx, &event, sizeof(event));
return 0;
}
)";
// Define the same struct to use in user space.
struct event_t {
int pid;
char name[16];
uint64_t old_addr;
uint64_t new_addr;
};
void handle_output(void* cb_cookie, void* data, int data_size) {
auto event = static_cast<event_t*>(data);
std::cout << "PID " << event->pid << " (" << event->name << ") ";
std::cout << "folly::RequestContext switch from " << event->old_addr << " to "
<< event->new_addr << std::endl;
}
ebpf::BPF* bpf;
void signal_handler(int s) {
std::cerr << "Terminating..." << std::endl;
delete bpf;
exit(0);
}
int main(int argc, char** argv) {
if (argc != 2) {
std::cout << "USAGE: FollyRequestContextSwitch PATH_TO_BINARY" << std::endl;
exit(1);
}
std::string binary_path(argv[1]);
bpf = new ebpf::BPF();
std::vector<ebpf::USDT> u;
u.emplace_back(binary_path, "folly", "request_context_switch_before",
"on_context_switch");
auto init_res = bpf->init(BPF_PROGRAM, {}, u);
if (init_res.code() != 0) {
std::cerr << init_res.msg() << std::endl;
return 1;
}
auto attach_res = bpf->attach_usdt(u[0]);
if (attach_res.code() != 0) {
std::cerr << attach_res.msg() << std::endl;
return 1;
}
auto open_res = bpf->open_perf_buffer("events", &handle_output);
if (open_res.code() != 0) {
std::cerr << open_res.msg() << std::endl;
return 1;
}
signal(SIGINT, signal_handler);
std::cout << "Started tracing, hit Ctrl-C to terminate." << std::endl;
while (true)
bpf->poll_perf_buffer("events");
return 0;
}