Rollup merge of #107596 - Kobzol:stage-build-timer, r=Mark-Simulacrum

Add nicer output to PGO build timer

This PR modifies the timer used in the PGO build script to contain nicer, hierarchical output of the individual build steps. It's not trivial to test locally, so I'll fire up a dist build right away.

r? ``@Mark-Simulacrum``

src/ci/stage-build.py

@@ -15,10 +15,9 @@ import sys
 import time
 import traceback
 import urllib.request
-from collections import OrderedDict
 from io import StringIO
 from pathlib import Path
-from typing import Callable, Dict, Iterable, List, Optional, Union
+from typing import Callable, Dict, Iterable, Iterator, List, Optional, Tuple, Union
 
 PGO_HOST = os.environ["PGO_HOST"]
 
@@ -204,48 +203,105 @@ class WindowsPipeline(Pipeline):
         return False
 
 
+def get_timestamp() -> float:
+    return time.time()
+
+
+Duration = float
+TimerSection = Union[Duration, "Timer"]
+
+
+def iterate_sections(section: TimerSection, name: str, level: int = 0) -> Iterator[Tuple[int, str, Duration]]:
+    """
+    Hierarchically iterate the sections of a timer, in a depth-first order.
+    """
+    if isinstance(section, Duration):
+        yield (level, name, section)
+    elif isinstance(section, Timer):
+        yield (level, name, section.total_duration())
+        for (child_name, child_section) in section.sections:
+            yield from iterate_sections(child_section, child_name, level=level + 1)
+    else:
+        assert False
+
+
 class Timer:
-    def __init__(self):
-        # We want this dictionary to be ordered by insertion.
-        # We use `OrderedDict` for compatibility with older Python versions.
-        self.stages = OrderedDict()
+    def __init__(self, parent_names: Tuple[str, ...] = ()):
+        self.sections: List[Tuple[str, TimerSection]] = []
+        self.section_active = False
+        self.parent_names = parent_names
 
     @contextlib.contextmanager
-    def stage(self, name: str):
-        assert name not in self.stages
+    def section(self, name: str) -> "Timer":
+        assert not self.section_active
+        self.section_active = True
 
-        start = time.time()
+        start = get_timestamp()
         exc = None
+
+        child_timer = Timer(parent_names=self.parent_names + (name, ))
+        full_name = " > ".join(child_timer.parent_names)
         try:
-            LOGGER.info(f"Stage `{name}` starts")
-            yield
+            LOGGER.info(f"Section `{full_name}` starts")
+            yield child_timer
         except BaseException as exception:
             exc = exception
             raise
         finally:
-            end = time.time()
+            end = get_timestamp()
             duration = end - start
-            self.stages[name] = duration
-            if exc is None:
-                LOGGER.info(f"Stage `{name}` ended: OK ({duration:.2f}s)")
+
+            if child_timer.has_children():
+                self.sections.append((name, child_timer))
             else:
-                LOGGER.info(f"Stage `{name}` ended: FAIL ({duration:.2f}s)")
+                self.sections.append((name, duration))
+            if exc is None:
+                LOGGER.info(f"Section `{full_name}` ended: OK ({duration:.2f}s)")
+            else:
+                LOGGER.info(f"Section `{full_name}` ended: FAIL ({duration:.2f}s)")
+            self.section_active = False
+
+    def total_duration(self) -> Duration:
+        duration = 0
+        for (_, section) in self.sections:
+            if isinstance(section, Duration):
+                duration += section
+            else:
+                duration += section.total_duration()
+        return duration
+
+    def has_children(self) -> bool:
+        return len(self.sections) > 0
 
     def print_stats(self):
-        total_duration = sum(self.stages.values())
+        rows = []
+        for (child_name, child_section) in self.sections:
+            for (level, name, duration) in iterate_sections(child_section, child_name, level=0):
+                label = f"{' ' * level}{name}:"
+                rows.append((label, duration))
 
-        # 57 is the width of the whole table
-        divider = "-" * 57
+        # Empty row
+        rows.append(("", ""))
+
+        total_duration_label = "Total duration:"
+        total_duration = self.total_duration()
+        rows.append((total_duration_label, humantime(total_duration)))
+
+        space_after_label = 2
+        max_label_length = max(16, max(len(label) for (label, _) in rows)) + space_after_label
+
+        table_width = max_label_length + 23
+        divider = "-" * table_width
 
         with StringIO() as output:
             print(divider, file=output)
-            for (name, duration) in self.stages.items():
-                pct = (duration / total_duration) * 100
-                name_str = f"{name}:"
-                print(f"{name_str:<34} {duration:>12.2f}s ({pct:>5.2f}%)", file=output)
-
-            total_duration_label = "Total duration:"
-            print(f"{total_duration_label:<34} {total_duration:>12.2f}s", file=output)
+            for (label, duration) in rows:
+                if isinstance(duration, Duration):
+                    pct = (duration / total_duration) * 100
+                    value = f"{duration:>12.2f}s ({pct:>5.2f}%)"
+                else:
+                    value = f"{duration:>{len(total_duration_label) + 7}}"
+                print(f"{label:<{max_label_length}} {value}", file=output)
             print(divider, file=output, end="")
             LOGGER.info(f"Timer results\n{output.getvalue()}")
 
@@ -265,6 +321,21 @@ def change_cwd(dir: Path):
         os.chdir(cwd)
 
 
+def humantime(time_s: float) -> str:
+    hours = time_s // 3600
+    time_s = time_s % 3600
+    minutes = time_s // 60
+    seconds = time_s % 60
+
+    result = ""
+    if hours > 0:
+        result += f"{int(hours)}h "
+    if minutes > 0:
+        result += f"{int(minutes)}m "
+    result += f"{round(seconds)}s"
+    return result
+
+
 def move_path(src: Path, dst: Path):
     LOGGER.info(f"Moving `{src}` to `{dst}`")
     shutil.move(src, dst)
@@ -585,15 +656,16 @@ def execute_build_pipeline(timer: Timer, pipeline: Pipeline, final_build_args: L
     pipeline.build_rustc_perf()
 
     # Stage 1: Build rustc + PGO instrumented LLVM
-    with timer.stage("Build rustc (LLVM PGO)"):
-        build_rustc(pipeline, args=[
-            "--llvm-profile-generate"
-        ], env=dict(
-            LLVM_PROFILE_DIR=str(pipeline.llvm_profile_dir_root() / "prof-%p")
-        ))
+    with timer.section("Stage 1 (LLVM PGO)") as stage1:
+        with stage1.section("Build rustc and LLVM"):
+            build_rustc(pipeline, args=[
+                "--llvm-profile-generate"
+            ], env=dict(
+                LLVM_PROFILE_DIR=str(pipeline.llvm_profile_dir_root() / "prof-%p")
+            ))
 
-    with timer.stage("Gather profiles (LLVM PGO)"):
-        gather_llvm_profiles(pipeline)
+        with stage1.section("Gather profiles"):
+            gather_llvm_profiles(pipeline)
 
     clear_llvm_files(pipeline)
     final_build_args += [
@@ -602,14 +674,15 @@ def execute_build_pipeline(timer: Timer, pipeline: Pipeline, final_build_args: L
     ]
 
     # Stage 2: Build PGO instrumented rustc + LLVM
-    with timer.stage("Build rustc (rustc PGO)"):
-        build_rustc(pipeline, args=[
-            "--rust-profile-generate",
-            pipeline.rustc_profile_dir_root()
-        ])
+    with timer.section("Stage 2 (rustc PGO)") as stage2:
+        with stage2.section("Build rustc and LLVM"):
+            build_rustc(pipeline, args=[
+                "--rust-profile-generate",
+                pipeline.rustc_profile_dir_root()
+            ])
 
-    with timer.stage("Gather profiles (rustc PGO)"):
-        gather_rustc_profiles(pipeline)
+        with stage2.section("Gather profiles"):
+            gather_rustc_profiles(pipeline)
 
     clear_llvm_files(pipeline)
     final_build_args += [
@@ -619,14 +692,15 @@ def execute_build_pipeline(timer: Timer, pipeline: Pipeline, final_build_args: L
 
     # Stage 3: Build rustc + BOLT instrumented LLVM
     if pipeline.supports_bolt():
-        with timer.stage("Build rustc (LLVM BOLT)"):
-            build_rustc(pipeline, args=[
-                "--llvm-profile-use",
-                pipeline.llvm_profile_merged_file(),
-                "--llvm-bolt-profile-generate",
-            ])
-        with timer.stage("Gather profiles (LLVM BOLT)"):
-            gather_llvm_bolt_profiles(pipeline)
+        with timer.section("Stage 3 (LLVM BOLT)") as stage3:
+            with stage3.section("Build rustc and LLVM"):
+                build_rustc(pipeline, args=[
+                    "--llvm-profile-use",
+                    pipeline.llvm_profile_merged_file(),
+                    "--llvm-bolt-profile-generate",
+                ])
+            with stage3.section("Gather profiles"):
+                gather_llvm_bolt_profiles(pipeline)
 
         clear_llvm_files(pipeline)
         final_build_args += [
@@ -635,7 +709,7 @@ def execute_build_pipeline(timer: Timer, pipeline: Pipeline, final_build_args: L
         ]
 
     # Stage 4: Build PGO optimized rustc + PGO/BOLT optimized LLVM
-    with timer.stage("Final build"):
+    with timer.section("Stage 4 (final build)"):
         cmd(final_build_args)