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#!/usr/bin/python3
# Generate Intel taken branches Linux perf event script for autofdo profiling.
# Copyright (C) 2016-2024 Free Software Foundation, Inc.
#
# GCC 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 3, or (at your option) any later
# version.
#
# GCC 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 GCC; see the file COPYING3. If not see
# <http://www.gnu.org/licenses/>.
# Run it with perf record -b -e EVENT program ...
# The Linux Kernel needs to support the PMU of the current CPU, and
# It will likely not work in VMs.
# Add --all to print for all cpus, otherwise for current cpu.
# Add --script to generate shell script to run correct event.
#
# Requires internet (https) access. This may require setting up a proxy
# with export https_proxy=...
#
import urllib.request
import sys
import json
import argparse
import collections
import os
import fnmatch
baseurl = "https://raw.githubusercontent.com/intel/perfmon/main"
target_events = ('BR_INST_RETIRED.NEAR_TAKEN',
'BR_INST_EXEC.TAKEN',
'BR_INST_RETIRED.TAKEN_JCC',
'BR_INST_TYPE_RETIRED.COND_TAKEN')
ap = argparse.ArgumentParser()
ap.add_argument('--all', '-a', help='Print for all CPUs', action='store_true')
ap.add_argument('--script', help='Generate shell script', action='store_true')
args = ap.parse_args()
eventmap = collections.defaultdict(list)
def get_cpustr():
cpuinfo = os.getenv("CPUINFO")
if cpuinfo is None:
cpuinfo = '/proc/cpuinfo'
f = open(cpuinfo, 'r')
cpu = [None, None, None, None]
for j in f:
n = j.split()
if n[0] == 'vendor_id':
cpu[0] = n[2]
elif n[0] == 'model' and n[1] == ':':
cpu[2] = int(n[2])
elif n[0] == 'cpu' and n[1] == 'family':
cpu[1] = int(n[3])
elif n[0] == 'stepping' and n[1] == ':':
cpu[3] = int(n[2])
if all(v is not None for v in cpu):
break
# stepping for SKX only
stepping = cpu[0] == "GenuineIntel" and cpu[1] == 6 and cpu[2] == 0x55
if stepping:
return "%s-%d-%X-%X" % tuple(cpu)
return "%s-%d-%X" % tuple(cpu)[:3]
def find_event(eventurl, model):
print("Downloading", eventurl, file = sys.stderr)
u = urllib.request.urlopen(eventurl)
events = json.loads(u.read())["Events"]
u.close()
found = 0
for j in events:
if j['EventName'] in target_events:
event = "cpu/event=%s,umask=%s/" % (j['EventCode'], j['UMask'])
if 'PEBS' in j and int(j['PEBS']) > 0:
event += "p"
if args.script:
eventmap[event].append(model)
else:
print(j['EventName'], "event for model", model, "is", event)
found += 1
return found
if not args.all:
cpu = get_cpustr()
if not cpu:
sys.exit("Unknown CPU type")
url = baseurl + "/mapfile.csv"
print("Downloading", url, file = sys.stderr)
u = urllib.request.urlopen(url)
found = 0
cpufound = 0
for j in u:
n = j.rstrip().decode().split(',')
if len(n) >= 4 and (args.all or fnmatch.fnmatch(cpu, n[0])) and n[3] == "core":
components = n[0].split("-")
model = components[2]
model = int(model, 16)
cpufound += 1
found += find_event(baseurl + n[2], model)
u.close()
if args.script:
print(r'''#!/bin/sh
# Profile workload for gcc profile feedback (autofdo) using Linux perf.
# Auto generated. To regenerate for new CPUs run
# contrib/gen_autofdo_event.py --script --all in gcc source
# usages:
# gcc-auto-profile program (profile program and children)
# gcc-auto-profile -a sleep X (profile all for X secs, may need root)
# gcc-auto-profile -p PID sleep X (profile PID)
# gcc-auto-profile --kernel -a sleep X (profile kernel)
# gcc-auto-profile --all -a sleep X (profile kernel and user space)
# Identify branches taken event for CPU.
#
FLAGS=u
if [ "$1" = "--kernel" ] ; then
FLAGS=k
shift
fi
if [ "$1" = "--all" ] ; then
FLAGS=uk
shift
fi
if ! grep -q Intel /proc/cpuinfo ; then
echo >&2 "Only Intel CPUs supported"
exit 1
fi
if grep -q hypervisor /proc/cpuinfo ; then
echo >&2 "Warning: branch profiling may not be functional in VMs"
fi
case `grep -E -q "^cpu family\s*: 6" /proc/cpuinfo &&
grep -E "^model\s*:" /proc/cpuinfo | head -n1` in''')
for event, mod in eventmap.items():
for m in mod[:-1]:
print("model*:\ %s|\\" % m)
print(r'model*:\ %s) E="%s$FLAGS" ;;' % (mod[-1], event))
print(r'''*)
if perf list br_inst_retired | grep -q br_inst_retired.near_taken ; then
E=br_inst_retired.near_taken:p
else
echo >&2 "Unknown CPU. Run contrib/gen_autofdo_event.py --all --script to update script."
exit 1
fi ;;''')
print(r"esac")
print(r"set -x")
print(r'if ! perf record -e $E -b "$@" ; then')
print(r' # PEBS may not actually be working even if the processor supports it')
print(r' # (e.g., in a virtual machine). Trying to run without /p.')
print(r' set +x')
print(r' echo >&2 "Retrying without /p."')
print(r' E="$(echo "${E}" | sed -e \'s/\/p/\//\ -e s/:p//)"')
print(r' set -x')
print(r' exec perf record -e $E -b "$@"')
print(r' set +x')
print(r'fi')
if cpufound == 0 and not args.all:
sys.exit('CPU %s not found' % cpu)
if found == 0:
sys.exit('Branch event not found')
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