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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

99
scripts/stack.py
View File

@@ -4,7 +4,7 @@
# report as infinite stack usage.
#
# Example:
# ./scripts/stack.py lfs.ci lfs_util.ci -S
# ./scripts/stack.py lfs.ci lfs_util.ci -Slimit
#
# Copyright (c) 2022, The littlefs authors.
# SPDX-License-Identifier: BSD-3-Clause
@@ -131,6 +131,7 @@ def openio(path, mode='r'):
return open(path, mode)
def collect(paths, *,
sources=None,
everything=False,
**args):
# parse the vcg format
@@ -181,8 +182,9 @@ def collect(paths, *,
if (not args.get('quiet')
and 'static' not in type
and 'bounded' not in type):
print("warning: found non-static stack for %s (%s)"
% (function, type, size))
print("warning: "
"found non-static stack for %s (%s, %s)" % (
function, type, size))
_, _, _, targets = callgraph[info['title']]
callgraph[info['title']] = (
file, function, int(size), targets)
@@ -193,11 +195,48 @@ def collect(paths, *,
else:
continue
callgraph_ = co.defaultdict(lambda: (None, None, 0, set()))
for source, (s_file, s_function, frame, targets) in callgraph.items():
# discard internal functions
if not everything and s_function.startswith('__'):
continue
# ignore filtered sources
if sources is not None:
if not any(
os.path.abspath(s_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(s_file)]) == os.getcwd():
continue
# smiplify path
if os.path.commonpath([
os.getcwd(),
os.path.abspath(s_file)]) == os.getcwd():
s_file = os.path.relpath(s_file)
else:
s_file = os.path.abspath(s_file)
callgraph_[source] = (s_file, s_function, frame, targets)
callgraph = callgraph_
if not everything:
for source, (s_file, s_function, _, _) in list(callgraph.items()):
callgraph_ = co.defaultdict(lambda: (None, None, 0, set()))
for source, (s_file, s_function, frame, targets) in callgraph.items():
# discard filtered sources
if sources is not None and not any(
os.path.abspath(s_file) == os.path.abspath(s)
for s in sources):
continue
# discard internal functions
if s_file.startswith('<') or s_file.startswith('/usr/include'):
del callgraph[source]
if s_function.startswith('__'):
continue
callgraph_[source] = (s_file, s_function, frame, targets)
callgraph = callgraph_
# find maximum stack size recursively, this requires also detecting cycles
# (in case of recursion)
@@ -278,7 +317,7 @@ def table(Result, results, diff_results=None, *,
all=False,
percent=False,
tree=False,
depth=None,
depth=1,
**_):
all_, all = all, __builtins__.all
@@ -467,15 +506,8 @@ def table(Result, results, diff_results=None, *,
# adjust the name width based on the expected call depth, though
# note this doesn't really work with unbounded recursion
if not summary:
# it doesn't really make sense to not have a depth with tree,
# so assume depth=inf if tree by default
if depth is None:
depth = m.inf if tree else 0
elif depth == 0:
depth = m.inf
if not m.isinf(depth):
widths[0] += 4*depth
widths[0] += 4*(depth-1)
# print our table with optional call info
#
@@ -528,7 +560,7 @@ def table(Result, results, diff_results=None, *,
prefixes[2+is_last] + "'-> ",
prefixes[2+is_last] + "| ",
prefixes[2+is_last] + " "))
recurse(names, depth)
recurse(names, depth-1)
if not tree:
print('%-*s %s%s' % (
@@ -544,6 +576,13 @@ def main(ci_paths,
defines=None,
sort=None,
**args):
# it doesn't really make sense to not have a depth with tree,
# so assume depth=inf if tree by default
if args.get('depth') is None:
args['depth'] = m.inf if args['tree'] else 1
elif args.get('depth') == 0:
args['depth'] = m.inf
# find sizes
if not args.get('use', None):
# find .ci files
@@ -588,13 +627,16 @@ def main(ci_paths,
# write results to CSV
if args.get('output'):
with openio(args['output'], 'w') as f:
writer = csv.DictWriter(f, StackResult._by
writer = csv.DictWriter(f,
(by if by is not None else StackResult._by)
+ ['stack_'+k for k in StackResult._fields])
writer.writeheader()
for r in results:
writer.writerow(
{k: getattr(r, k) for k in StackResult._by}
| {'stack_'+k: getattr(r, k) for k in StackResult._fields})
{k: getattr(r, k)
for k in (by if by is not None else StackResult._by)}
| {'stack_'+k: getattr(r, k)
for k in StackResult._fields})
# find previous results?
if args.get('diff'):
@@ -636,7 +678,8 @@ if __name__ == "__main__":
import argparse
import sys
parser = argparse.ArgumentParser(
description="Find stack usage at the function level.")
description="Find stack usage at the function level.",
allow_abbrev=False)
parser.add_argument(
'ci_paths',
nargs='*',
@@ -703,7 +746,13 @@ 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(
@@ -711,20 +760,16 @@ if __name__ == "__main__":
action='store_true',
help="Only show the function call tree.")
parser.add_argument(
'-L', '--depth',
'-Z', '--depth',
nargs='?',
type=lambda x: int(x, 0),
const=0,
help="Depth of function calls to show. 0 show all calls but may not "
help="Depth of function calls to show. 0 shows all calls but may not "
"terminate!")
parser.add_argument(
'-e', '--error-on-recursion',
action='store_true',
help="Error if any functions are recursive.")
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}))