1 //! # Rust Compiler Self-Profiling
3 //! This module implements the basic framework for the compiler's self-
4 //! profiling support. It provides the `SelfProfiler` type which enables
5 //! recording "events". An event is something that starts and ends at a given
6 //! point in time and has an ID and a kind attached to it. This allows for
7 //! tracing the compiler's activity.
9 //! Internally this module uses the custom tailored [measureme][mm] crate for
10 //! efficiently recording events to disk in a compact format that can be
11 //! post-processed and analyzed by the suite of tools in the `measureme`
12 //! project. The highest priority for the tracing framework is on incurring as
13 //! little overhead as possible.
18 //! Events have a few properties:
20 //! - The `event_kind` designates the broad category of an event (e.g. does it
21 //! correspond to the execution of a query provider or to loading something
22 //! from the incr. comp. on-disk cache, etc).
23 //! - The `event_id` designates the query invocation or function call it
24 //! corresponds to, possibly including the query key or function arguments.
25 //! - Each event stores the ID of the thread it was recorded on.
26 //! - The timestamp stores beginning and end of the event, or the single point
27 //! in time it occurred at for "instant" events.
30 //! ## Event Filtering
32 //! Event generation can be filtered by event kind. Recording all possible
33 //! events generates a lot of data, much of which is not needed for most kinds
34 //! of analysis. So, in order to keep overhead as low as possible for a given
35 //! use case, the `SelfProfiler` will only record the kinds of events that
36 //! pass the filter specified as a command line argument to the compiler.
39 //! ## `event_id` Assignment
41 //! As far as `measureme` is concerned, `event_id`s are just strings. However,
42 //! it would incur too much overhead to generate and persist each `event_id`
43 //! string at the point where the event is recorded. In order to make this more
44 //! efficient `measureme` has two features:
46 //! - Strings can share their content, so that re-occurring parts don't have to
47 //! be copied over and over again. One allocates a string in `measureme` and
48 //! gets back a `StringId`. This `StringId` is then used to refer to that
49 //! string. `measureme` strings are actually DAGs of string components so that
50 //! arbitrary sharing of substrings can be done efficiently. This is useful
51 //! because `event_id`s contain lots of redundant text like query names or
52 //! def-path components.
54 //! - `StringId`s can be "virtual" which means that the client picks a numeric
55 //! ID according to some application-specific scheme and can later make that
56 //! ID be mapped to an actual string. This is used to cheaply generate
57 //! `event_id`s while the events actually occur, causing little timing
58 //! distortion, and then later map those `StringId`s, in bulk, to actual
59 //! `event_id` strings. This way the largest part of the tracing overhead is
60 //! localized to one contiguous chunk of time.
62 //! How are these `event_id`s generated in the compiler? For things that occur
63 //! infrequently (e.g. "generic activities"), we just allocate the string the
64 //! first time it is used and then keep the `StringId` in a hash table. This
65 //! is implemented in `SelfProfiler::get_or_alloc_cached_string()`.
67 //! For queries it gets more interesting: First we need a unique numeric ID for
68 //! each query invocation (the `QueryInvocationId`). This ID is used as the
69 //! virtual `StringId` we use as `event_id` for a given event. This ID has to
70 //! be available both when the query is executed and later, together with the
71 //! query key, when we allocate the actual `event_id` strings in bulk.
73 //! We could make the compiler generate and keep track of such an ID for each
74 //! query invocation but luckily we already have something that fits all the
75 //! the requirements: the query's `DepNodeIndex`. So we use the numeric value
76 //! of the `DepNodeIndex` as `event_id` when recording the event and then,
77 //! just before the query context is dropped, we walk the entire query cache
78 //! (which stores the `DepNodeIndex` along with the query key for each
79 //! invocation) and allocate the corresponding strings together with a mapping
80 //! for `DepNodeIndex as StringId`.
82 //! [mm]: https://github.com/rust-lang/measureme/
85 use crate::fx::FxHashMap;
87 use std::borrow::Borrow;
88 use std::collections::hash_map::Entry;
89 use std::convert::Into;
90 use std::error::Error;
95 use std::time::{Duration, Instant};
97 pub use measureme::EventId;
98 use measureme::{EventIdBuilder, Profiler, SerializableString, StringId};
99 use parking_lot::RwLock;
101 bitflags::bitflags! {
102 struct EventFilter: u32 {
103 const GENERIC_ACTIVITIES = 1 << 0;
104 const QUERY_PROVIDERS = 1 << 1;
105 const QUERY_CACHE_HITS = 1 << 2;
106 const QUERY_BLOCKED = 1 << 3;
107 const INCR_CACHE_LOADS = 1 << 4;
109 const QUERY_KEYS = 1 << 5;
110 const FUNCTION_ARGS = 1 << 6;
112 const INCR_RESULT_HASHING = 1 << 8;
114 const DEFAULT = Self::GENERIC_ACTIVITIES.bits |
115 Self::QUERY_PROVIDERS.bits |
116 Self::QUERY_BLOCKED.bits |
117 Self::INCR_CACHE_LOADS.bits |
118 Self::INCR_RESULT_HASHING.bits;
120 const ARGS = Self::QUERY_KEYS.bits | Self::FUNCTION_ARGS.bits;
124 // keep this in sync with the `-Z self-profile-events` help message in rustc_session/options.rs
125 const EVENT_FILTERS_BY_NAME: &[(&str, EventFilter)] = &[
126 ("none", EventFilter::empty()),
127 ("all", EventFilter::all()),
128 ("default", EventFilter::DEFAULT),
129 ("generic-activity", EventFilter::GENERIC_ACTIVITIES),
130 ("query-provider", EventFilter::QUERY_PROVIDERS),
131 ("query-cache-hit", EventFilter::QUERY_CACHE_HITS),
132 ("query-blocked", EventFilter::QUERY_BLOCKED),
133 ("incr-cache-load", EventFilter::INCR_CACHE_LOADS),
134 ("query-keys", EventFilter::QUERY_KEYS),
135 ("function-args", EventFilter::FUNCTION_ARGS),
136 ("args", EventFilter::ARGS),
137 ("llvm", EventFilter::LLVM),
138 ("incr-result-hashing", EventFilter::INCR_RESULT_HASHING),
141 /// Something that uniquely identifies a query invocation.
142 pub struct QueryInvocationId(pub u32);
144 /// A reference to the SelfProfiler. It can be cloned and sent across thread
145 /// boundaries at will.
147 pub struct SelfProfilerRef {
148 // This field is `None` if self-profiling is disabled for the current
149 // compilation session.
150 profiler: Option<Arc<SelfProfiler>>,
152 // We store the filter mask directly in the reference because that doesn't
153 // cost anything and allows for filtering with checking if the profiler is
155 event_filter_mask: EventFilter,
157 // Print verbose generic activities to stdout
158 print_verbose_generic_activities: bool,
160 // Print extra verbose generic activities to stdout
161 print_extra_verbose_generic_activities: bool,
164 impl SelfProfilerRef {
166 profiler: Option<Arc<SelfProfiler>>,
167 print_verbose_generic_activities: bool,
168 print_extra_verbose_generic_activities: bool,
169 ) -> SelfProfilerRef {
170 // If there is no SelfProfiler then the filter mask is set to NONE,
171 // ensuring that nothing ever tries to actually access it.
172 let event_filter_mask =
173 profiler.as_ref().map_or(EventFilter::empty(), |p| p.event_filter_mask);
178 print_verbose_generic_activities,
179 print_extra_verbose_generic_activities,
183 // This shim makes sure that calls only get executed if the filter mask
184 // lets them pass. It also contains some trickery to make sure that
185 // code is optimized for non-profiling compilation sessions, i.e. anything
186 // past the filter check is never inlined so it doesn't clutter the fast
189 fn exec<F>(&self, event_filter: EventFilter, f: F) -> TimingGuard<'_>
191 F: for<'a> FnOnce(&'a SelfProfiler) -> TimingGuard<'a>,
194 fn cold_call<F>(profiler_ref: &SelfProfilerRef, f: F) -> TimingGuard<'_>
196 F: for<'a> FnOnce(&'a SelfProfiler) -> TimingGuard<'a>,
198 let profiler = profiler_ref.profiler.as_ref().unwrap();
202 if unlikely!(self.event_filter_mask.contains(event_filter)) {
209 /// Start profiling a verbose generic activity. Profiling continues until the
210 /// VerboseTimingGuard returned from this call is dropped. In addition to recording
211 /// a measureme event, "verbose" generic activities also print a timing entry to
212 /// stdout if the compiler is invoked with -Ztime or -Ztime-passes.
213 pub fn verbose_generic_activity<'a>(
215 event_label: &'static str,
216 ) -> VerboseTimingGuard<'a> {
218 if self.print_verbose_generic_activities { Some(event_label.to_owned()) } else { None };
220 VerboseTimingGuard::start(message, self.generic_activity(event_label))
223 /// Start profiling an extra verbose generic activity. Profiling continues until the
224 /// VerboseTimingGuard returned from this call is dropped. In addition to recording
225 /// a measureme event, "extra verbose" generic activities also print a timing entry to
226 /// stdout if the compiler is invoked with -Ztime-passes.
227 pub fn extra_verbose_generic_activity<'a, A>(
229 event_label: &'static str,
231 ) -> VerboseTimingGuard<'a>
233 A: Borrow<str> + Into<String>,
235 let message = if self.print_extra_verbose_generic_activities {
236 Some(format!("{}({})", event_label, event_arg.borrow()))
241 VerboseTimingGuard::start(message, self.generic_activity_with_arg(event_label, event_arg))
244 /// Start profiling a generic activity. Profiling continues until the
245 /// TimingGuard returned from this call is dropped.
247 pub fn generic_activity(&self, event_label: &'static str) -> TimingGuard<'_> {
248 self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
249 let event_label = profiler.get_or_alloc_cached_string(event_label);
250 let event_id = EventId::from_label(event_label);
251 TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
255 /// Start profiling with some event filter for a given event. Profiling continues until the
256 /// TimingGuard returned from this call is dropped.
258 pub fn generic_activity_with_event_id(&self, event_id: EventId) -> TimingGuard<'_> {
259 self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
260 TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
264 /// Start profiling a generic activity. Profiling continues until the
265 /// TimingGuard returned from this call is dropped.
267 pub fn generic_activity_with_arg<A>(
269 event_label: &'static str,
273 A: Borrow<str> + Into<String>,
275 self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
276 let builder = EventIdBuilder::new(&profiler.profiler);
277 let event_label = profiler.get_or_alloc_cached_string(event_label);
278 let event_id = if profiler.event_filter_mask.contains(EventFilter::FUNCTION_ARGS) {
279 let event_arg = profiler.get_or_alloc_cached_string(event_arg);
280 builder.from_label_and_arg(event_label, event_arg)
282 builder.from_label(event_label)
284 TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
289 pub fn generic_activity_with_args(
291 event_label: &'static str,
292 event_args: &[String],
293 ) -> TimingGuard<'_> {
294 self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
295 let builder = EventIdBuilder::new(&profiler.profiler);
296 let event_label = profiler.get_or_alloc_cached_string(event_label);
297 let event_id = if profiler.event_filter_mask.contains(EventFilter::FUNCTION_ARGS) {
298 let event_args: Vec<_> = event_args
300 .map(|s| profiler.get_or_alloc_cached_string(&s[..]))
302 builder.from_label_and_args(event_label, &event_args)
304 builder.from_label(event_label)
306 TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
310 /// Start profiling a query provider. Profiling continues until the
311 /// TimingGuard returned from this call is dropped.
313 pub fn query_provider(&self) -> TimingGuard<'_> {
314 self.exec(EventFilter::QUERY_PROVIDERS, |profiler| {
315 TimingGuard::start(profiler, profiler.query_event_kind, EventId::INVALID)
319 /// Record a query in-memory cache hit.
321 pub fn query_cache_hit(&self, query_invocation_id: QueryInvocationId) {
322 self.instant_query_event(
323 |profiler| profiler.query_cache_hit_event_kind,
325 EventFilter::QUERY_CACHE_HITS,
329 /// Start profiling a query being blocked on a concurrent execution.
330 /// Profiling continues until the TimingGuard returned from this call is
333 pub fn query_blocked(&self) -> TimingGuard<'_> {
334 self.exec(EventFilter::QUERY_BLOCKED, |profiler| {
335 TimingGuard::start(profiler, profiler.query_blocked_event_kind, EventId::INVALID)
339 /// Start profiling how long it takes to load a query result from the
340 /// incremental compilation on-disk cache. Profiling continues until the
341 /// TimingGuard returned from this call is dropped.
343 pub fn incr_cache_loading(&self) -> TimingGuard<'_> {
344 self.exec(EventFilter::INCR_CACHE_LOADS, |profiler| {
347 profiler.incremental_load_result_event_kind,
353 /// Start profiling how long it takes to hash query results for incremental compilation.
354 /// Profiling continues until the TimingGuard returned from this call is dropped.
356 pub fn incr_result_hashing(&self) -> TimingGuard<'_> {
357 self.exec(EventFilter::INCR_RESULT_HASHING, |profiler| {
360 profiler.incremental_result_hashing_event_kind,
367 fn instant_query_event(
369 event_kind: fn(&SelfProfiler) -> StringId,
370 query_invocation_id: QueryInvocationId,
371 event_filter: EventFilter,
373 drop(self.exec(event_filter, |profiler| {
374 let event_id = StringId::new_virtual(query_invocation_id.0);
375 let thread_id = std::thread::current().id().as_u64().get() as u32;
377 profiler.profiler.record_instant_event(
378 event_kind(profiler),
379 EventId::from_virtual(event_id),
387 pub fn with_profiler(&self, f: impl FnOnce(&SelfProfiler)) {
388 if let Some(profiler) = &self.profiler {
393 /// Gets a `StringId` for the given string. This method makes sure that
394 /// any strings going through it will only be allocated once in the
396 /// Returns `None` if the self-profiling is not enabled.
397 pub fn get_or_alloc_cached_string(&self, s: &str) -> Option<StringId> {
398 self.profiler.as_ref().map(|p| p.get_or_alloc_cached_string(s))
402 pub fn enabled(&self) -> bool {
403 self.profiler.is_some()
407 pub fn llvm_recording_enabled(&self) -> bool {
408 self.event_filter_mask.contains(EventFilter::LLVM)
411 pub fn get_self_profiler(&self) -> Option<Arc<SelfProfiler>> {
412 self.profiler.clone()
416 pub struct SelfProfiler {
418 event_filter_mask: EventFilter,
420 string_cache: RwLock<FxHashMap<String, StringId>>,
422 query_event_kind: StringId,
423 generic_activity_event_kind: StringId,
424 incremental_load_result_event_kind: StringId,
425 incremental_result_hashing_event_kind: StringId,
426 query_blocked_event_kind: StringId,
427 query_cache_hit_event_kind: StringId,
432 output_directory: &Path,
433 crate_name: Option<&str>,
434 event_filters: &Option<Vec<String>>,
435 ) -> Result<SelfProfiler, Box<dyn Error + Send + Sync>> {
436 fs::create_dir_all(output_directory)?;
438 let crate_name = crate_name.unwrap_or("unknown-crate");
439 let filename = format!("{}-{}.rustc_profile", crate_name, process::id());
440 let path = output_directory.join(&filename);
441 let profiler = Profiler::new(&path)?;
443 let query_event_kind = profiler.alloc_string("Query");
444 let generic_activity_event_kind = profiler.alloc_string("GenericActivity");
445 let incremental_load_result_event_kind = profiler.alloc_string("IncrementalLoadResult");
446 let incremental_result_hashing_event_kind =
447 profiler.alloc_string("IncrementalResultHashing");
448 let query_blocked_event_kind = profiler.alloc_string("QueryBlocked");
449 let query_cache_hit_event_kind = profiler.alloc_string("QueryCacheHit");
451 let mut event_filter_mask = EventFilter::empty();
453 if let Some(ref event_filters) = *event_filters {
454 let mut unknown_events = vec![];
455 for item in event_filters {
456 if let Some(&(_, mask)) =
457 EVENT_FILTERS_BY_NAME.iter().find(|&(name, _)| name == item)
459 event_filter_mask |= mask;
461 unknown_events.push(item.clone());
465 // Warn about any unknown event names
466 if !unknown_events.is_empty() {
467 unknown_events.sort();
468 unknown_events.dedup();
471 "Unknown self-profiler events specified: {}. Available options are: {}.",
472 unknown_events.join(", "),
473 EVENT_FILTERS_BY_NAME
475 .map(|&(name, _)| name.to_string())
481 event_filter_mask = EventFilter::DEFAULT;
487 string_cache: RwLock::new(FxHashMap::default()),
489 generic_activity_event_kind,
490 incremental_load_result_event_kind,
491 incremental_result_hashing_event_kind,
492 query_blocked_event_kind,
493 query_cache_hit_event_kind,
497 /// Allocates a new string in the profiling data. Does not do any caching
498 /// or deduplication.
499 pub fn alloc_string<STR: SerializableString + ?Sized>(&self, s: &STR) -> StringId {
500 self.profiler.alloc_string(s)
503 /// Gets a `StringId` for the given string. This method makes sure that
504 /// any strings going through it will only be allocated once in the
506 pub fn get_or_alloc_cached_string<A>(&self, s: A) -> StringId
508 A: Borrow<str> + Into<String>,
510 // Only acquire a read-lock first since we assume that the string is
511 // already present in the common case.
513 let string_cache = self.string_cache.read();
515 if let Some(&id) = string_cache.get(s.borrow()) {
520 let mut string_cache = self.string_cache.write();
521 // Check if the string has already been added in the small time window
522 // between dropping the read lock and acquiring the write lock.
523 match string_cache.entry(s.into()) {
524 Entry::Occupied(e) => *e.get(),
525 Entry::Vacant(e) => {
526 let string_id = self.profiler.alloc_string(&e.key()[..]);
532 pub fn map_query_invocation_id_to_string(&self, from: QueryInvocationId, to: StringId) {
533 let from = StringId::new_virtual(from.0);
534 self.profiler.map_virtual_to_concrete_string(from, to);
537 pub fn bulk_map_query_invocation_id_to_single_string<I>(&self, from: I, to: StringId)
539 I: Iterator<Item = QueryInvocationId> + ExactSizeIterator,
541 let from = from.map(|qid| StringId::new_virtual(qid.0));
542 self.profiler.bulk_map_virtual_to_single_concrete_string(from, to);
545 pub fn query_key_recording_enabled(&self) -> bool {
546 self.event_filter_mask.contains(EventFilter::QUERY_KEYS)
549 pub fn event_id_builder(&self) -> EventIdBuilder<'_> {
550 EventIdBuilder::new(&self.profiler)
555 pub struct TimingGuard<'a>(Option<measureme::TimingGuard<'a>>);
557 impl<'a> TimingGuard<'a> {
560 profiler: &'a SelfProfiler,
561 event_kind: StringId,
563 ) -> TimingGuard<'a> {
564 let thread_id = std::thread::current().id().as_u64().get() as u32;
565 let raw_profiler = &profiler.profiler;
567 raw_profiler.start_recording_interval_event(event_kind, event_id, thread_id);
568 TimingGuard(Some(timing_guard))
572 pub fn finish_with_query_invocation_id(self, query_invocation_id: QueryInvocationId) {
573 if let Some(guard) = self.0 {
575 let event_id = StringId::new_virtual(query_invocation_id.0);
576 let event_id = EventId::from_virtual(event_id);
577 guard.finish_with_override_event_id(event_id);
583 pub fn none() -> TimingGuard<'a> {
588 pub fn run<R>(self, f: impl FnOnce() -> R) -> R {
595 pub struct VerboseTimingGuard<'a> {
596 start_and_message: Option<(Instant, Option<usize>, String)>,
597 _guard: TimingGuard<'a>,
600 impl<'a> VerboseTimingGuard<'a> {
601 pub fn start(message: Option<String>, _guard: TimingGuard<'a>) -> Self {
604 start_and_message: message.map(|msg| (Instant::now(), get_resident_set_size(), msg)),
609 pub fn run<R>(self, f: impl FnOnce() -> R) -> R {
615 impl Drop for VerboseTimingGuard<'_> {
617 if let Some((start_time, start_rss, ref message)) = self.start_and_message {
618 let end_rss = get_resident_set_size();
619 print_time_passes_entry(&message[..], start_time.elapsed(), start_rss, end_rss);
624 pub fn print_time_passes_entry(
627 start_rss: Option<usize>,
628 end_rss: Option<usize>,
630 let rss_to_mb = |rss| (rss as f64 / 1_000_000.0).round() as usize;
631 let rss_change_to_mb = |rss| (rss as f64 / 1_000_000.0).round() as i128;
633 let mem_string = match (start_rss, end_rss) {
634 (Some(start_rss), Some(end_rss)) => {
635 let change_rss = end_rss as i128 - start_rss as i128;
638 "; rss: {:>4}MB -> {:>4}MB ({:>+5}MB)",
639 rss_to_mb(start_rss),
641 rss_change_to_mb(change_rss),
644 (Some(start_rss), None) => format!("; rss start: {:>4}MB", rss_to_mb(start_rss)),
645 (None, Some(end_rss)) => format!("; rss end: {:>4}MB", rss_to_mb(end_rss)),
646 (None, None) => String::new(),
649 eprintln!("time: {:>7}{}\t{}", duration_to_secs_str(dur), mem_string, what);
652 // Hack up our own formatting for the duration to make it easier for scripts
653 // to parse (always use the same number of decimal places and the same unit).
654 pub fn duration_to_secs_str(dur: std::time::Duration) -> String {
655 format!("{:.3}", dur.as_secs_f64())
661 pub fn get_resident_set_size() -> Option<usize> {
662 use std::mem::{self, MaybeUninit};
663 use winapi::shared::minwindef::DWORD;
664 use winapi::um::processthreadsapi::GetCurrentProcess;
665 use winapi::um::psapi::{GetProcessMemoryInfo, PROCESS_MEMORY_COUNTERS};
667 let mut pmc = MaybeUninit::<PROCESS_MEMORY_COUNTERS>::uninit();
669 GetProcessMemoryInfo(GetCurrentProcess(), pmc.as_mut_ptr(), mem::size_of_val(&pmc) as DWORD)
673 let pmc = unsafe { pmc.assume_init() };
674 Some(pmc.WorkingSetSize as usize)
678 } else if #[cfg(unix)] {
679 pub fn get_resident_set_size() -> Option<usize> {
681 let contents = fs::read("/proc/self/statm").ok()?;
682 let contents = String::from_utf8(contents).ok()?;
683 let s = contents.split_whitespace().nth(field)?;
684 let npages = s.parse::<usize>().ok()?;
688 pub fn get_resident_set_size() -> Option<usize> {