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use std::env;
use std::fmt;
use std::fs::File;
use std::io;
use std::io::prelude::*;
use std::io::BufReader;
use std::process::Command;
#[derive(Debug, Clone)]
struct BlockedEvent {
ns: u64,
stacktrace: Vec<String>,
}
const TIME_UNITS: &[&str] = &[
"ns",
"us",
"ms",
"sec",
];
impl fmt::Display for BlockedEvent {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut ns = self.ns as f64;
let mut u = 0;
while ns > 10000.0 && u + 1 < TIME_UNITS.len() {
ns /= 1000.0;
u += 1;
}
write!(f, "{:>6.1}{}", ns, TIME_UNITS[u])?;
for (idx, e) in self.stacktrace.iter().enumerate() {
if idx != 0 {
write!(f, " =>")?;
}
write!(f, " {}", e)?;
}
Ok(())
}
}
const STACK_START_FILTER: &[&str] = &[
"trace_event_raw_event_sched_blocked",
"__schedule",
"schedule",
];
const STACK_END_FILTER: &[&str] = &[
"entry_SYSCALL_64_after_hwframe",
"do_syscall_64",
"__x86_sys_",
"syscall_exit_to_user_mode",
"ret_from_fork",
"kthread",
"worker_thread",
];
const STACK_FILTER: &[&[&str]] = &[
&["schedule_idle", "do_idle"],
&["read_events", "do_io_getevents"],
&["schedule_idle", "do_idle"],
&["__cond_resched", "process_one_work"],
&["schedule_timeout", "rcu_gp_fqs_loop", "rcu_gp_kthread"],
&["ring_buffer_wait", "tracing_wait_pipe"],
&["do_epoll_wait"],
&["worker_thread"],
&["smpboot_thread_fn"],
];
fn fn_matches(l: &str, r: &str) -> bool {
let idx = r.find(|c: char| c == '.' || c == '/' || c == '+');
l == if let Some(idx) = idx {
&r[..idx]
} else {
&r[..]
}
}
fn should_skip_event(ev: &BlockedEvent) -> bool {
if ev.stacktrace.is_empty() {
return true;
}
STACK_FILTER.iter()
.any(|i| i.iter()
.zip(ev.stacktrace.iter())
.all(|(l, r)| fn_matches(l, r)))
}
fn event_trim(ev: &mut BlockedEvent) {
while ev.stacktrace.len() > 1 {
let l = ev.stacktrace.last().unwrap();
if STACK_END_FILTER.iter().any(|i| fn_matches(i, &l[..])) {
ev.stacktrace.pop();
} else {
break;
}
}
}
fn read_trace(mut child: std::process::Child) -> io::Result<Vec<BlockedEvent>> {
let tracepoint_name = "sched_blocked: ";
let trace_pipe = File::open("/sys/kernel/debug/tracing/trace_pipe")
.map_err(|e| {eprintln!("error opening trace: {}", e); e})?;
let mut lines = BufReader::new(trace_pipe)
.lines()
.filter_map(|i| i.ok())
.peekable();
let mut evs: Vec<BlockedEvent> = Vec::new();
while let Some(line) = lines.next() {
let idx = line.rfind(tracepoint_name);
if idx.is_none() {
continue;
}
let idx = idx.unwrap() + tracepoint_name.len();
let mut ev = BlockedEvent {
ns: line[idx..].parse().unwrap(),
stacktrace: Vec::new(),
};
let line = lines.next_if(|i| i.find("<stack trace>").is_some());
if line.is_none() {
continue;
}
let mut skip = STACK_START_FILTER.iter();
while let Some(line) = lines.next_if(|i| i.starts_with(" => ")) {
let func = &line[4..];
let s = skip.next();
if s.is_none() || !fn_matches(s.unwrap(), func) {
ev.stacktrace.push(func.to_string());
skip.all(|_i| true);
}
}
event_trim(&mut ev);
if !should_skip_event(&ev) {
evs.push(ev);
}
match child.try_wait() {
Err(_e) => break,
Ok(Some(_status)) => break,
Ok(None) => continue,
}
}
Ok(evs)
}
fn run_trace(args: Vec<String>) -> io::Result<()> {
std::fs::write("/sys/kernel/debug/tracing/trace", "")
.map_err(|e| {eprintln!("error clearing trace: {}", e); e})?;
std::fs::write("/sys/kernel/debug/tracing/buffer_size_kb", "8192")
.map_err(|e| {eprintln!("error writing buffer size: {}", e); e})?;
std::fs::write("/sys/kernel/debug/tracing/set_event", "sched:sched_blocked")
.map_err(|e| {eprintln!("error setting event: {}", e); e})?;
std::fs::write("/sys/kernel/debug/tracing/events/sched/sched_blocked/trigger", "stacktrace").ok();
std::fs::write("/sys/kernel/debug/tracing/trace_options", "sym-offset")
.map_err(|e| {eprintln!("error setting sym-offset: {}", e); e})?;
std::fs::write("/sys/kernel/debug/tracing/tracing_on", "1")
.map_err(|e| {eprintln!("error enabling tracing: {}", e); e})?;
let child = Command::new(&args[0])
.args(&args[1..])
.spawn()
.expect(&format!("Failed to start child process {}", args[0]));
let mut evs = read_trace(child)?;
evs.sort_by(|l, r| l.ns.cmp(&r.ns));
println!("\nIndividual events:");
for i in evs.iter().rev().take(30) {
println!("{}", i);
}
evs.sort_by(|l, r| l.stacktrace.cmp(&r.stacktrace));
let mut evs_folded: Vec<BlockedEvent> = Vec::new();
for i in evs.iter() {
if let Some(l) = evs_folded.last_mut() {
if l.stacktrace == i.stacktrace {
l.ns += i.ns;
} else {
evs_folded.push(i.clone());
}
} else {
evs_folded.push(i.clone());
}
}
evs_folded.sort_by(|l, r| l.ns.cmp(&r.ns));
println!("\nAggregate blocked time:");
for i in evs_folded.iter().rev().take(30) {
println!("{}", i);
}
Ok(())
}
fn main() {
let args = env::args();
let args: Vec<String> = args.skip(1).collect();
run_trace(args).ok();
}
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