From 7b8c5efa52161bcd99006e7986c6cb67f6475023 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Fri, 22 Apr 2016 16:32:24 +0100
Subject: [PATCH] tests: Add boot-benchmark-range script.
Add a script we can use to benchmark performance across a range of
commits in another project.
(cherry picked from commit 8299d7087a6457828a57ecace54c01b73912a9c7)
---
docs/guestfs-performance.pod | 14 +++
tests/qemu/boot-benchmark-range.pl | 240 +++++++++++++++++++++++++++++++++++++
2 files changed, 254 insertions(+)
create mode 100755 tests/qemu/boot-benchmark-range.pl
diff --git a/docs/guestfs-performance.pod b/docs/guestfs-performance.pod
index cf30fdc..d9c76ac 100644
--- a/docs/guestfs-performance.pod
+++ b/docs/guestfs-performance.pod
@@ -589,6 +589,20 @@ breakpoints, etc. Note that when you are past the BIOS and into the
Linux kernel, you'll want to change the architecture back to 32 or 64
bit.
+=head1 PERFORMANCE REGRESSIONS IN OTHER PROGRAMS
+
+Sometimes performance regressions happen in other programs (eg. qemu,
+the kernel) that cause problems for libguestfs.
+
+In the libguestfs source, F<tests/qemu/boot-benchmark-range.pl> is a
+script which can be used to benchmark libguestfs across a range of git
+commits in another project to find out if any commit is causing a
+slowdown (or speedup).
+
+To find out how to use this script, consult the manual:
+
+ ./tests/qemu/boot-benchmark-range.pl --man
+
=head1 SEE ALSO
L<supermin(1)>,
diff --git a/tests/qemu/boot-benchmark-range.pl b/tests/qemu/boot-benchmark-range.pl
new file mode 100755
index 0000000..0e31c4d
--- /dev/null
+++ b/tests/qemu/boot-benchmark-range.pl
@@ -0,0 +1,240 @@
+#!/usr/bin/env perl
+# Copyright (C) 2016 Red Hat Inc.
+#
+# 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, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+use warnings;
+use strict;
+
+use Pod::Usage;
+use Getopt::Long;
+
+=head1 NAME
+
+boot-benchmark-range.pl - Benchmark libguestfs across a range of commits
+from another project
+
+=head1 SYNOPSIS
+
+ LIBGUESTFS_BACKEND=direct \
+ LIBGUESTFS_HV=/path/to/qemu/x86_64-softmmu/qemu-system-x86_64 \
+ ./run \
+ tests/qemu/boot-benchmark-range.pl /path/to/qemu HEAD~50..HEAD
+
+=head1
+
+Run F<tests/qemu/boot-benchmark> across a range of commits in another
+project. This is useful for finding performance regressions in other
+programs such as qemu or the Linux kernel which might be affecting
+libguestfs.
+
+For example, suppose you suspect there has been a performance
+regression in qemu, somewhere between C<HEAD~50..HEAD>. You could run
+the script like this:
+
+ LIBGUESTFS_BACKEND=direct \
+ LIBGUESTFS_HV=/path/to/qemu/x86_64-softmmu/qemu-system-x86_64 \
+ ./run \
+ tests/qemu/boot-benchmark-range.pl /path/to/qemu HEAD~50..HEAD
+
+where F</path/to/qemu> is the path to the qemu git repository.
+
+The output is a list of the qemu commits, annotated by the benchmark
+time and some other information about how the time compares to the
+previous commit.
+
+You should run these tests on an unloaded machine. In particular
+running a desktop environment, web browser and so on can make the
+benchmarks useless.
+
+=head1 OPTIONS
+
+=over 4
+
+=cut
+
+my $help;
+
+=item B<--help>
+
+Display brief help.
+
+=cut
+
+my $man;
+
+=item B<--man>
+
+Display full documentation (man page).
+
+=cut
+
+my $benchmark_command;
+
+=item B<--benchmark> C<boot-benchmark>
+
+Set the name of the benchmark to run. You only need to use this if
+the script cannot find the right path to the libguestfs
+F<tests/qemu/boot-benchmark> program. By default the script looks for
+this file in the same directory as its executable.
+
+=cut
+
+my $make_command = "make";
+
+=item B<--make> C<make>
+
+Set the command used to build the other project. The default is
+to run C<make>.
+
+If the command fails, then the commit is skipped.
+
+=back
+
+=cut
+
+# Clean up the program name.
+my $progname = $0;
+$progname =~ s{.*/}{};
+
+# Parse options.
+GetOptions ("help|?" => \$help,
+ "man" => \$man,
+ "benchmark=s" => \$benchmark_command,
+ "make=s" => \$make_command,
+ ) or pod2usage (2);
+pod2usage (-exitval => 0) if $help;
+pod2usage (-exitval => 0, -verbose => 2) if $man;
+
+die "$progname: missing argument: requires path to git repository and range of commits\n" unless @ARGV == 2;
+
+my $dir = $ARGV[0];
+my $range = $ARGV[1];
+
+die "$progname: $dir is not a git repository\n"
+ unless -d $dir && -d "$dir/.git";
+
+sub silently_run
+{
+ open my $saveout, ">&STDOUT";
+ open my $saveerr, ">&STDERR";
+ open STDOUT, ">/dev/null";
+ open STDERR, ">/dev/null";
+ my $ret = system (@_);
+ open STDOUT, ">&", $saveout;
+ open STDERR, ">&", $saveerr;
+ return $ret;
+}
+
+# Find the benchmark program and check it works.
+unless (defined $benchmark_command) {
+ $benchmark_command = $0;
+ $benchmark_command =~ s{/[^/]+$}{};
+ $benchmark_command .= "/boot-benchmark";
+
+ my $r = silently_run ("$benchmark_command", "--help");
+ die "$progname: cannot locate boot-benchmark program, try using --benchmark\n" unless $r == 0;
+}
+
+# Get the top-most commit from the remote, and restore it on exit.
+my $top_commit = `git -C '$dir' rev-parse HEAD`;
+chomp $top_commit;
+
+sub checkout
+{
+ my $sha = shift;
+ my $ret = silently_run ("git", "-C", $dir, "checkout", $sha);
+ return $ret;
+}
+
+END {
+ checkout ($top_commit);
+}
+
+# Get the range of commits and log messages.
+my @range = ();
+open RANGE, "git -C '$dir' log --reverse --oneline $range |" or die;
+while (<RANGE>) {
+ if (m/^([0-9a-f]+) (.*)/) {
+ my $sha = $1;
+ my $msg = $2;
+ push @range, [ $sha, $msg ];
+ }
+}
+close RANGE or die;
+
+# Run the test.
+my $prev_ms;
+foreach (@range) {
+ my ($sha, $msg) = @$_;
+ my $r;
+
+ print "\n";
+ print "$sha $msg\n";
+
+ # Checkout this commit in the other repo.
+ $r = checkout ($sha);
+ if ($r != 0) {
+ print "git checkout failed\n";
+ next;
+ }
+
+ # Build the repo, silently.
+ $r = silently_run ("cd $dir && $make_command");
+ if ($r != 0) {
+ print "build failed\n";
+ next;
+ }
+
+ # Run the benchmark program and get the timing.
+ my ($time_ms, $time_str);
+ open BENCHMARK, "$benchmark_command | grep '^Result:' |" or die;
+ while (<BENCHMARK>) {
+ die unless m/^Result: (([\d.]+)ms ±[\d.]+ms)/;
+ $time_ms = $2;
+ $time_str = $1;
+ }
+ close BENCHMARK;
+
+ print "\t", $time_str;
+ if (defined $prev_ms) {
+ if ($prev_ms > $time_ms) {
+ my $pc = 100 * ($prev_ms-$time_ms) / $time_ms;
+ if ($pc >= 1) {
+ printf (" ↑ improves performance by %0.1f%%", $pc);
+ }
+ } elsif ($prev_ms < $time_ms) {
+ my $pc = 100 * ($time_ms-$prev_ms) / $prev_ms;
+ if ($pc >= 1) {
+ printf (" ↓ degrades performance by %0.1f%%", $pc);
+ }
+ }
+ }
+ print "\n";
+ $prev_ms = $time_ms;
+}
+
+=head1 SEE ALSO
+
+L<git(1)>,
+L<guestfs-performance(1)>.
+
+=head1 AUTHOR
+
+Richard W.M. Jones.
+
+=head1 COPYRIGHT
+
+Copyright (C) 2016 Red Hat Inc.
--
2.7.4