Hi, Ahmed.
Yes, somewhat related to John's hints on these comments, it is customary to have just a brief description before "Copyright" lines. This means one sentence, or a short paragraph (3-4 sentences max). The lenghty syntax commemt should be, in my opinion, moved after the license preamble, just before the start of real Python code.
Thanks Mr. John and Aleksandar for your feedback. I will update the script accordingly.
One question:
What is the behavior in case of the executable architecture and "target" command line option mismatch (for example, one specifies m68k target, but passes hppa executable? Would that be detected before bisect search, or the bisect procedure will be applied even though such cases do not make sense?
The script will exit with an error of something along the lines of "Invalid ELF image for this architecture".
This is done before starting "bisect" and after the initial "configure" and "make".
Yours, Aleksandar
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+import argparse
+import multiprocessing
+import tempfile
+import os
+import shutil
+import subprocess
+import sys
+
+
+############################ GIT WRAPPERS ############################
+def git_bisect(qemu_path, command, args=None):
+ """
+ Wrapper function for running git bisect.
+
+ Parameters:
+ qemu_path (str): QEMU path.
+ command (str): bisect command (start|fast|slow|reset).
+ args (list): Optional arguments.
+
+ Returns:
+ (str): git bisect stdout.
+ """
+ process = ["git", "bisect", command]
+ if args:
+ process += args
+ bisect = subprocess.run(process,
+ cwd=qemu_path,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE)
+ if bisect.returncode:
+ sys.exit(bisect.stderr.decode("utf-8"))
+ return bisect.stdout.decode("utf-8")
+
+
+def git_checkout(commit, qemu_path):
+ """
+ Wrapper function for checking out a given git commit.
+
+ Parameters:
+ commit (str): Commit hash of a git commit.
+ qemu_path (str): QEMU path.
+ """
+ checkout_commit = subprocess.run(["git",
+ "checkout",
+ commit],
+ cwd=qemu_path,
+ stdout=subprocess.DEVNULL,
+ stderr=subprocess.PIPE)
+ if checkout_commit.returncode:
+ sys.exit(checkout_commit.stderr.decode("utf-8"))
+
+
+def git_clone(qemu_path):
+ """
+ Wrapper function for cloning QEMU git repo from GitHub.
+
+ Parameters:
+ qemu_path (str): Path to clone the QEMU repo to.
+ """
+ clone_qemu = subprocess.run(["git",
+ "clone",
+ "https://github.com/qemu/qemu.git",
+ qemu_path],
+ stderr=subprocess.STDOUT)
+ if clone_qemu.returncode:
+ sys.exit("Failed to clone QEMU!")
+######################################################################
+
+
+def check_requirements(tool):
+ """
+ Verify that all script requirements are installed (perf|callgrind & git).
+
+ Parameters:
+ tool (str): Tool used for the measurement (perf or callgrind).
+ """
+ if tool == "perf":
+ check_perf_installation = subprocess.run(["which", "perf"],
+ stdout=subprocess.DEVNULL)
+ if check_perf_installation.returncode:
+ sys.exit("Please install perf before running the script.")
+
+ # Insure user has previllage to run perf
+ check_perf_executability = subprocess.run(["perf", "stat", "ls", "/"],
+ stdout=subprocess.DEVNULL,
+ stderr=subprocess.DEVNULL)
+ if check_perf_executability.returncode:
+ sys.exit("""
+ Error:
+ You may not have permission to collect stats.
+ Consider tweaking /proc/sys/kernel/perf_event_paranoid,
+ which controls use of the performance events system by
+ unprivileged users (without CAP_SYS_ADMIN).
+ -1: Allow use of (almost) all events by all users
+ Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
+ 0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN
+ Disallow raw tracepoint access by users without CAP_SYS_ADMIN
+ 1: Disallow CPU event access by users without CAP_SYS_ADMIN
+ 2: Disallow kernel profiling by users without CAP_SYS_ADMIN
+ To make this setting permanent, edit /etc/sysctl.conf too, e.g.:
+ kernel.perf_event_paranoid = -1
+
+ *Alternatively, you can run this script under sudo privileges.
+ """)
+ elif tool == "callgrind":
+ check_valgrind_installation = subprocess.run(["which", "valgrind"],
+ stdout=subprocess.DEVNULL)
+ if check_valgrind_installation.returncode:
+ sys.exit("Please install valgrind before running the script.")
+
+ # Insure that git is installed
+ check_git_installation = subprocess.run(["which", "git"],
+ stdout=subprocess.DEVNULL)
+ if check_git_installation.returncode:
+ sys.exit("Please install git before running the script.")
+
+
+def make(qemu_build_path):
+ """
+ Build QEMU by running the Makefile.
+
+ Parameters:
+ qemu_build_path (str): Path to the build directory with configuration files.
+ """
+ run_make = subprocess.run(["make",
+ "-j",
+ str(multiprocessing.cpu_count())],
+ cwd=qemu_build_path,
+ stdout=subprocess.DEVNULL,
+ stderr=subprocess.PIPE)
+ if run_make.returncode:
+ sys.exit(run_make.stderr.decode("utf-8"))
+
+
+def measure_instructions(tool, qemu_exe_path, command):
+ """
+ Measure the number of instructions when running an program with QEMU.
+
+ Parameters:
+ tool (str): Tool used for the measurement (perf|callgrind).
+ qemu_exe_path (str): Path to the QEMU executable of the equivalent target.
+ command (list): Program path and arguments.
+
+ Returns:
+ (int): Number of instructions.
+ """
+ if tool == "perf":
+ run_perf = subprocess.run((["perf",
+ "stat",
+ "-x",
+ " ",
+ "-e",
+ "instructions",
+ qemu_exe_path]
+ + command),
+ stdout=subprocess.DEVNULL,
+ stderr=subprocess.PIPE)
+ if run_perf.returncode:
+ sys.exit(run_perf.stderr.decode("utf-8"))
+ else:
+ perf_output = run_perf.stderr.decode("utf-8").split(" ")
+ return int(perf_output[0])
+
+ elif tool == "callgrind":
+ with tempfile.NamedTemporaryFile() as tmpfile:
+ run_callgrind = subprocess.run((["valgrind",
+ "--tool=callgrind",
+ "--callgrind-out-file={}".format(
+ tmpfile.name),
+ qemu_exe_path]
+ + command),
+ stdout=subprocess.DEVNULL,
+ stderr=subprocess.PIPE)
+ if run_callgrind.returncode:
+ sys.exit(run_callgrind.stderr.decode("utf-8"))
+ else:
+ callgrind_output = run_callgrind.stderr.decode("utf-8").split("\n")
+ return int(callgrind_output[8].split(" ")[-1])
+
+
+def main():
+ # Parse the command line arguments
+ parser = argparse.ArgumentParser(
+ usage="bisect.py [-h] -s,--start START [-e,--end END] [-q,--qemu QEMU] "
+ "--target TARGET --tool {perf,callgrind} -- "
+ "<target executable> [<target executable options>]")
+
+ parser.add_argument("-s", "--start", dest="start", type=str, required=True,
+ help="First commit hash in the search range")
+ parser.add_argument("-e", "--end", dest="end", type=str, default="master",
+ help="Last commit hash in the search range")
+ parser.add_argument("-q", "--qemu", dest="qemu", type=str, default="",
+ help="QEMU path")
+ parser.add_argument("--target", dest="target", type=str, required=True,
+ help="QEMU target")
+ parser.add_argument("--tool", dest="tool", choices=["perf", "callgrind"],
+ required=True, help="Tool used for measurements")
+
+ parser.add_argument("command", type=str, nargs="+", help=argparse.SUPPRESS)
+
+ args = parser.parse_args()
+
+ # Extract the needed variables from the args
+ start_commit = args.start
+ end_commit = args.end
+ qemu = args.qemu
+ target = args.target
+ tool = args.tool
+ command = args.command
+
+ # Set QEMU path
+ if qemu == "":
+ # Create a temp directory for cloning QEMU
+ tmpdir = tempfile.TemporaryDirectory()
+ qemu_path = os.path.join(tmpdir.name, "qemu")
+
+ # Clone QEMU into the temporary directory
+ print("Fetching QEMU: ", end="", flush=True)
+ git_clone(qemu_path)
+ print()
+ else:
+ qemu_path = qemu
+
+ # Create the build directory
+ qemu_build_path = os.path.join(qemu_path, "tmp-build-gcc")
+ if not os.path.exists(qemu_build_path):
+ os.mkdir(qemu_build_path)
+ else:
+ sys.exit("A build directory with the same name (tmp-build-gcc) used in "
+ "the script is already in the provided QEMU path.")
+
+ qemu_exe_path = os.path.join(qemu_build_path,
+ "{}-linux-user".format(target),
+ "qemu-{}".format(target))
+
+ # Configure QEMU
+ configure = subprocess.run(["../configure",
+ "--target-list={}-linux-user".format(target)],
+ cwd=qemu_build_path,
+ stdout=subprocess.DEVNULL,
+ stderr=subprocess.PIPE)
+ if configure.returncode:
+ sys.exit(configure.stderr.decode("utf-8"))
+
+ # Do performance measurements for the start commit
+ git_checkout(start_commit, qemu_path)
+ make(qemu_build_path)
+ start_commit_instructions = measure_instructions(tool,
+ qemu_exe_path,
+ command)
+ print("{:<30} {}".format("Start Commit Instructions:",
+ format(start_commit_instructions, ",")))
+
+ # Do performance measurements for the end commit
+ git_checkout(end_commit, qemu_path)
+ make(qemu_build_path)
+ end_commit_instructions = measure_instructions(tool,
+ qemu_exe_path,
+ command)
+ print("{:<30} {}".format("End Commit Instructions:",
+ format(end_commit_instructions, ",")))
+
+ # Calculate performance difference between start and end commits
+ performance_difference = \
+ (start_commit_instructions - end_commit_instructions) / \
+ max(end_commit_instructions, start_commit_instructions) * 100
+ performance_change = "+" if performance_difference > 0 else "-"
+ print("{:<30} {}".format("Performance Change:",
+ performance_change +
+ str(round(abs(performance_difference), 3))+"%"))
+
+ # Set the custom terms used for progressing in "git bisect"
+ term_old = "fast" if performance_difference < 0 else "slow"
+ term_new = "slow" if term_old == "fast" else "fast"
+
+ # Start git bisect
+ git_bisect(qemu_path, "start", [
+ "--term-old", term_old, "--term-new", term_new])
+ # Set start commit state
+ git_bisect(qemu_path, term_old, [start_commit])
+ # Set end commit state
+ bisect_output = git_bisect(qemu_path, term_new, [end_commit])
+ # Print estimated bisect steps
+ print("\n{:<30} {}\n".format(
+ "Estimated Number of Steps:", bisect_output.split()[9]))
+
+ # Initialize bisect_count to track the number of performed
+ bisect_count = 1
+
+ while True:
+ print("**************BISECT STEP {}**************".format(bisect_count))
+
+ make(qemu_build_path)
+
+ instructions = measure_instructions(tool, qemu_exe_path, command)
+ # Find the difference between the current instructions and start/end
+ # instructions.
+ diff_end = abs(instructions - end_commit_instructions)
+ diff_start = abs(instructions - start_commit_instructions)
+
+ # If current number of insructions is closer to that of start,
+ # set current commit as term_old.
+ # Else, set current commit as term_new.
+ if diff_end > diff_start:
+ bisect_command = term_old
+ else:
+ bisect_command = term_new
+
+ print("{:<20} {}".format("Instructions:", format(instructions, ",")))
+ print("{:<20} {}".format("Status:", "{} commit".format(bisect_command)))
+
+ bisect_output = git_bisect(qemu_path, bisect_command)
+
+ # Continue if still bisecting,
+ # else, print result and break.
+ if not bisect_output.split(" ")[0] == "Bisecting:":
+ print("\n*****************BISECT RESULT*****************")
+ commit_message_start = bisect_output.find("commit\n") + 7
+ commit_message_end = bisect_output.find(":040000") - 1
+ print(bisect_output[commit_message_start:commit_message_end])
+ break
+
+ bisect_count += 1
+
+ # Reset git bisect
+ git_bisect(qemu_path, "reset")
+
+ # Delete temp build directory
+ shutil.rmtree(qemu_build_path)
+
+
+if __name__ == "__main__":
+ main()
--
2.17.1