6f4f30c840
* Add support for generating perf maps for simple perf profiling * add missing enum entry in C code * bugfix: use hexa when printing the code region's length too (thanks bjorn3!) * sanitize file name + use bufwriter * introduce --profile CLI flag for wasmtime * Update doc and doc comments for new --profile option * remove redundant FromStr import * Apply review feedback: make_line receives a Write impl, report errors * fix tests? * better docs
86 lines
3.0 KiB
Rust
86 lines
3.0 KiB
Rust
use crate::{CompiledModule, ProfilingAgent};
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use anyhow::Result;
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use std::io::{self, BufWriter, Write};
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use std::process;
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use std::{fs::File, sync::Mutex};
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use wasmtime_environ::EntityRef as _;
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/// Process-wide perf map file. Perf only reads a unique file per process.
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static PERFMAP_FILE: Mutex<Option<File>> = Mutex::new(None);
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/// Interface for driving the creation of jitdump files
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pub struct PerfMapAgent;
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impl PerfMapAgent {
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/// Intialize a JitDumpAgent and write out the header.
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pub fn new() -> Result<Self> {
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let mut file = PERFMAP_FILE.lock().unwrap();
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if file.is_none() {
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let filename = format!("/tmp/perf-{}.map", process::id());
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*file = Some(File::create(filename)?);
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}
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Ok(PerfMapAgent)
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}
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fn make_line(
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writer: &mut dyn Write,
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name: &str,
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addr: *const u8,
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len: usize,
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) -> io::Result<()> {
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// Format is documented here: https://github.com/torvalds/linux/blob/master/tools/perf/Documentation/jit-interface.txt
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// Try our best to sanitize the name, since wasm allows for any utf8 string in there.
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let sanitized_name = name.replace('\n', "_").replace('\r', "_");
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write!(writer, "{:x} {:x} {}\n", addr as usize, len, sanitized_name)?;
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Ok(())
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}
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}
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impl ProfilingAgent for PerfMapAgent {
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/// Sent when a method is compiled and loaded into memory by the VM.
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fn module_load(&self, module: &CompiledModule, _dbg_image: Option<&[u8]>) {
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let mut file = PERFMAP_FILE.lock().unwrap();
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let file = file.as_mut().unwrap();
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let mut file = BufWriter::new(file);
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for (idx, func) in module.finished_functions() {
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let addr = func.as_ptr();
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let len = func.len();
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let name = super::debug_name(module, idx);
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if let Err(err) = Self::make_line(&mut file, &name, addr, len) {
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eprintln!("Error when writing function info to the perf map file: {err}");
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return;
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}
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}
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// Note: these are the trampolines into exported functions.
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for (idx, func, len) in module.trampolines() {
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let (addr, len) = (func as usize as *const u8, len);
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let name = format!("wasm::trampoline[{}]", idx.index());
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if let Err(err) = Self::make_line(&mut file, &name, addr, len) {
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eprintln!("Error when writing export trampoline info to the perf map file: {err}");
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return;
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}
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}
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if let Err(err) = file.flush() {
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eprintln!("Error when flushing the perf map file buffer: {err}");
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}
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}
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fn load_single_trampoline(
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&self,
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name: &str,
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addr: *const u8,
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size: usize,
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_pid: u32,
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_tid: u32,
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) {
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let mut file = PERFMAP_FILE.lock().unwrap();
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let file = file.as_mut().unwrap();
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if let Err(err) = Self::make_line(file, name, addr, size) {
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eprintln!("Error when writing import trampoline info to the perf map file: {err}");
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}
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}
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}
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