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Added perf.py a wrapper around Linux's perf tool for perf sampling

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This provides 2 things:

1. perf integration with the bench/test runners - This is a bit tricky
   with perf as it doesn't have its own way to combine perf measurements
   across multiple processes. perf.py works around this by writing
   everything to a zip file, using flock to synchronize. As a plus, free
   compression!

2. Parsing and presentation of perf results in a format consistent with
   the other CSV-based tools. This actually ran into a surprising number of
   issues:

   - We need to process raw events to get the information we want, this
     ends up being a lot of data (~16MiB at 100Hz uncompressed), so we
     paralellize the parsing of each decompressed perf file.

   - perf reports raw addresses post-ASLR. It does provide sym+off which
     is very useful, but to find the source of static functions we need to
     reverse the ASLR by finding the delta the produces the best
     symbol<->addr matches.

   - This isn't related to perf, but decoding dwarf line-numbers is
     really complicated. You basically need to write a tiny VM.

This also turns on perf measurement by default for the bench-runner, but at a
low frequency (100 Hz). This can be decreased or removed in the future
if it causes any slowdown.
This commit is contained in:
Christopher Haster
2022-10-02 18:35:46 -05:00
parent ca66993812
commit 490e1c4616
15 changed files with 2104 additions and 283 deletions
Download Patch File Download Diff File Expand all files Collapse all files

105
scripts/coverage.py
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@ -3,7 +3,9 @@
# Script to find coverage info after running tests.
#
# Example:
# ./scripts/coverage.py lfs.t.a.gcda lfs_util.t.a.gcda -s
# ./scripts/coverage.py \
# lfs.t.a.gcda lfs_util.t.a.gcda \
# -Flfs.c -Flfs_util.c -slines
#
# Copyright (c) 2022, The littlefs authors.
# Copyright (c) 2020, Arm Limited. All rights reserved.
@ -209,19 +211,13 @@ def openio(path, mode='r'):
else:
return open(path, mode)
def collect(paths, *,
def collect(gcda_paths, *,
gcov_tool=GCOV_TOOL,
build_dir=None,
sources=None,
everything=False,
**args):
results = []
for path in paths:
# map to source file
src_path = re.sub('\.t\.a\.gcda$', '.c', path)
if build_dir:
src_path = re.sub('%s/*' % re.escape(build_dir), '',
src_path)
for path in gcda_paths:
# get coverage info through gcov's json output
# note, gcov-tool may contain extra args
cmd = GCOV_TOOL + ['-b', '-t', '--json-format', path]
@ -231,7 +227,8 @@ def collect(paths, *,
stdout=sp.PIPE,
stderr=sp.PIPE if not args.get('verbose') else None,
universal_newlines=True,
errors='replace')
errors='replace',
close_fds=False)
data = json.load(proc.stdout)
proc.wait()
if proc.returncode != 0:
@ -242,12 +239,30 @@ def collect(paths, *,
# collect line/branch coverage
for file in data['files']:
if file['file'] != src_path:
continue
# ignore filtered sources
if sources is not None:
if not any(
os.path.abspath(file['file']) == os.path.abspath(s)
for s in sources):
continue
else:
# default to only cwd
if not everything and not os.path.commonpath([
os.getcwd(),
os.path.abspath(file['file'])]) == os.getcwd():
continue
# simplify path
if os.path.commonpath([
os.getcwd(),
os.path.abspath(file['file'])]) == os.getcwd():
file_name = os.path.relpath(file['file'])
else:
file_name = os.path.abspath(file['file'])
for func in file['functions']:
func_name = func.get('name', '(inlined)')
# discard internal function (this includes injected test cases)
# discard internal functions (this includes injected test cases)
if not everything:
if func_name.startswith('__'):
continue
@ -255,7 +270,7 @@ def collect(paths, *,
# go ahead and add functions, later folding will merge this if
# there are other hits on this line
results.append(CoverageResult(
src_path, func_name, func['start_line'],
file_name, func_name, func['start_line'],
func['execution_count'], 0,
Frac(1 if func['execution_count'] > 0 else 0, 1),
0,
@ -271,7 +286,7 @@ def collect(paths, *,
# go ahead and add lines, later folding will merge this if
# there are other hits on this line
results.append(CoverageResult(
src_path, func_name, line['line_number'],
file_name, func_name, line['line_number'],
0, line['count'],
0,
Frac(1 if line['count'] > 0 else 0, 1),
@ -519,31 +534,25 @@ def table(Result, results, diff_results=None, *,
line[-1]))
def annotate(Result, results, paths, *,
def annotate(Result, results, *,
annotate=False,
lines=False,
branches=False,
build_dir=None,
**args):
# if neither branches/lines specified, color both
if annotate and not lines and not branches:
lines, branches = True, True
for path in paths:
# map to source file
src_path = re.sub('\.t\.a\.gcda$', '.c', path)
if build_dir:
src_path = re.sub('%s/*' % re.escape(build_dir), '',
src_path)
for path in co.OrderedDict.fromkeys(r.file for r in results).keys():
# flatten to line info
results = fold(Result, results, by=['file', 'line'])
table = {r.line: r for r in results if r.file == src_path}
table = {r.line: r for r in results if r.file == path}
# calculate spans to show
if not annotate:
spans = []
last = None
func = None
for line, r in sorted(table.items()):
if ((lines and int(r.hits) == 0)
or (branches and r.branches.a < r.branches.b)):
@ -553,27 +562,29 @@ def annotate(Result, results, paths, *,
line+1+args['context'])
else:
if last is not None:
spans.append(last)
spans.append((last, func))
last = range(
line-args['context'],
line+1+args['context'])
func = r.function
if last is not None:
spans.append(last)
spans.append((last, func))
with open(src_path) as f:
with open(path) as f:
skipped = False
for i, line in enumerate(f):
# skip lines not in spans?
if not annotate and not any(i+1 in s for s in spans):
if not annotate and not any(i+1 in s for s, _ in spans):
skipped = True
continue
if skipped:
skipped = False
print('%s@@ %s:%d @@%s' % (
print('%s@@ %s:%d: %s @@%s' % (
'\x1b[36m' if args['color'] else '',
src_path,
path,
i+1,
next(iter(f for _, f in spans)),
'\x1b[m' if args['color'] else ''))
# build line
@ -659,12 +670,14 @@ def main(gcda_paths, *,
# write results to CSV
if args.get('output'):
with openio(args['output'], 'w') as f:
writer = csv.DictWriter(f, CoverageResult._by
writer = csv.DictWriter(f,
(by if by is not None else CoverageResult._by)
+ ['coverage_'+k for k in CoverageResult._fields])
writer.writeheader()
for r in results:
writer.writerow(
{k: getattr(r, k) for k in CoverageResult._by}
{k: getattr(r, k)
for k in (by if by is not None else CoverageResult._by)}
| {'coverage_'+k: getattr(r, k)
for k in CoverageResult._fields})
@ -698,8 +711,7 @@ def main(gcda_paths, *,
or args.get('lines')
or args.get('branches')):
# annotate sources
annotate(CoverageResult, results, paths,
**args)
annotate(CoverageResult, results, **args)
else:
# print table
table(CoverageResult, results,
@ -724,7 +736,8 @@ if __name__ == "__main__":
import argparse
import sys
parser = argparse.ArgumentParser(
description="Find coverage info after running tests.")
description="Find coverage info after running tests.",
allow_abbrev=False)
parser.add_argument(
'gcda_paths',
nargs='*',
@ -791,15 +804,21 @@ if __name__ == "__main__":
action='store_true',
help="Only show the total.")
parser.add_argument(
'-A', '--everything',
'-F', '--source',
dest='sources',
action='append',
help="Only consider definitions in this file. Defaults to anything "
"in the current directory.")
parser.add_argument(
'--everything',
action='store_true',
help="Include builtin and libc specific symbols.")
parser.add_argument(
'-H', '--hits',
'--hits',
action='store_true',
help="Show total hits instead of coverage.")
parser.add_argument(
'-l', '--annotate',
'-A', '--annotate',
action='store_true',
help="Show source files annotated with coverage info.")
parser.add_argument(
@ -814,7 +833,7 @@ if __name__ == "__main__":
'-c', '--context',
type=lambda x: int(x, 0),
default=3,
help="Show a additional lines of context. Defaults to 3.")
help="Show n additional lines of context. Defaults to 3.")
parser.add_argument(
'-W', '--width',
type=lambda x: int(x, 0),
@ -838,10 +857,6 @@ if __name__ == "__main__":
default=GCOV_TOOL,
type=lambda x: x.split(),
help="Path to the gcov tool to use. Defaults to %r." % GCOV_TOOL)
parser.add_argument(
'--build-dir',
help="Specify the relative build directory. Used to map object files "
"to the correct source files.")
sys.exit(main(**{k: v
for k, v in vars(parser.parse_intermixed_args()).items()
if v is not None}))