Add --min-time option to set timing noise threshold

As requested by jnthn++.

analyze

@@ -46,6 +46,7 @@ sub MAIN {
 sub process_options_and_arguments {
     my %opt;
     GetOptions(\%opt, 'help|h|?!', 'man!', 'format=s', 'style=s', 'outfile=s',
+                      'min-time|min_time|mintime=f',
                       'ignore-startup|ignore_startup|ignorestartup!',
                       'ignore-compile|ignore_compile|ignorecompile!',
                       'skip-incomplete|skip_incomplete|skipincomplete!',
@@ -54,6 +55,8 @@ sub process_options_and_arguments {
     pod2usage(-verbose => 1) if $opt{help};
     pod2usage(-verbose => 2) if $opt{man};
 
+    $opt{'min-time'} //= 1e-2;
+
     $opt{outfile} //= '-';
     my $suffix      = (fileparse($opt{outfile}, qr/\.[^.]+$/))[2] || '.';
     my $ext         = lc substr $suffix, 1;
@@ -77,6 +80,7 @@ sub process_options_and_arguments {
 sub analyze_timings_files {
     my ($opt, $out_fh, @files) = @_;
 
+    my $min_time        = $opt->{'min-time'};
     my $ignore_startup  = $opt->{'ignore-startup'};
     my $ignore_compile  = $opt->{'ignore-compile'};
     my $skip_incomplete = $opt->{'skip-incomplete'};
@@ -86,9 +90,9 @@ sub analyze_timings_files {
         my $startup = $data->{run}{startup} || {};
 
         for my $test (@{$data->{times}}) {
-            $test->{compare} = compare_scaled_times($test->{best}, $startup,
-                                                    $ignore_startup,
-                                                    $ignore_compile);
+            $test->{compare}
+                = compare_scaled_times($test->{best}, $startup, $min_time,
+                                       $ignore_startup, $ignore_compile);
         }
         ($data->{score}, $data->{test_score})
             = compute_scores($data, $skip_incomplete);
@@ -196,8 +200,7 @@ sub load_timing_file {
 }
 
 sub compare_scaled_times {
-    my ($times, $startup, $ignore_startup, $ignore_compile) = @_;
-    my $min_time = 1e-2;
+    my ($times, $startup, $min_time, $ignore_startup, $ignore_compile) = @_;
     my $max_rate = 0;
     my %max_rates;
 
@@ -1331,6 +1334,7 @@ analyze -- Analyze benchmark data produced by timeall
     analyze [--help|-h|-?] [--man]
             [--format=text|json|html|html_snippet|html_plot]
             [--style=0|1|auto] [--outfile=path/to/file.ext]
+            [--min-time=0.01]
             [--ignore-startup] [--ignore-compile] [--skip-incomplete]
             [--compare] [--history]
             path/to/timing_file.json [path/to/second_timing_file.json ...]
@@ -1387,6 +1391,13 @@ default) if C<--outfile> is set to C<-> (a single hyphen).  If this option
 is set and C<--format> is not, then the summary format defaults to the
 lowercased extension (F<ext> in F<path/to/file.ext>) of the C<--outfile>.
 
+=item --min-time=0.01
+
+Set the noise floor for test timings, below which timing data will be
+ignored to avoid nonsensical rate calculations and wildly oscillating
+plots.  This filter considers the times after ignoring startup and/or
+compile times, and defaults to 0.01 seconds.
+
 =item --ignore-startup
 
 Ignore (subtract out) the startup time of the compiler from each benchmark

bench

@@ -357,12 +357,15 @@ multi MAIN ('time', *@components, :$variants?, :$tests?, :$tests-tagged?,
 
 #= Compare benchmark timings
 multi MAIN ('compare', *@timings, :$format?, :$style?, :$outfile?,
+            Numeric :$min-time,
             Bool :$ignore-startup = True, Bool :$ignore-compile = True,
             Bool :$skip-incomplete = True) {
     needs-timings('compare');
 
-    my @options = as-options(:compare, :$ignore-startup, :$ignore-compile,
-                             :$skip-incomplete, :$format, :$style, :$outfile);
+    my @options = as-options(:compare, :$min-time,
+                             :$ignore-startup, :$ignore-compile,
+                             :$skip-incomplete,
+                             :$format, :$style, :$outfile);
 
     my @timings-files;
     for explode-timings(@timings, :!chdir).kv -> $component, @files {
@@ -374,11 +377,12 @@ multi MAIN ('compare', *@timings, :$format?, :$style?, :$outfile?,
 
 #= Compare historical peak performance scores
 multi MAIN ('history', *@timings, :$format?, :$style?, :$outfile?,
+            Numeric :$min-time,
             Bool :$ignore-startup = True, Bool :$ignore-compile = True,
             Bool :$skip-incomplete = True) {
     needs-timings('show history');
 
-    my @options = as-options(:compare, :history,
+    my @options = as-options(:compare, :history, :$min-time,
                              :$ignore-startup, :$ignore-compile,
                              :$skip-incomplete,
                              :$format, :$style, :$outfile);