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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2015-08-20 11:53:30 +0200
committerMichal Marek <mmarek@suse.com>2015-08-28 17:04:40 +0200
commit5bbb9f753afe213aebc8dba30c7e2dbb73616b79 (patch)
tree70fd497c25222ffd604de186925d02c8a8c12178 /scripts/stackdelta
parentd523b255de60880304038006de5f93f2db612ad6 (diff)
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scripts: add stackdelta script
This adds a simple perl script for reading two files as produced by the stackusage script and computing the changes in stack usage. For example: $ scripts/stackusage -o /tmp/old.su CC=gcc-4.7 -j8 fs/ext4/ $ scripts/stackusage -o /tmp/new.su CC=gcc-5.0 -j8 fs/ext4/ $ scripts/stackdelta /tmp/{old,new}.su | sort -k5,5g shows that gcc 5.0 generally produces less stack-hungry code than gcc 4.7. Obviously, the script can also be used for measuring the effect of commits, .config tweaks or whatnot. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Michal Marek <mmarek@suse.com>
Diffstat (limited to 'scripts/stackdelta')
-rwxr-xr-xscripts/stackdelta59
1 files changed, 59 insertions, 0 deletions
diff --git a/scripts/stackdelta b/scripts/stackdelta
new file mode 100755
index 000000000000..48eabf2f48f8
--- /dev/null
+++ b/scripts/stackdelta
@@ -0,0 +1,59 @@
+#!/usr/bin/perl
+
+# Read two files produced by the stackusage script, and show the
+# delta between them.
+#
+# Currently, only shows changes for functions listed in both files. We
+# could add an option to show also functions which have vanished or
+# appeared (which would often be due to gcc making other inlining
+# decisions).
+#
+# Another possible option would be a minimum absolute value for the
+# delta.
+#
+# A third possibility is for sorting by delta, but that can be
+# achieved by piping to sort -k5,5g.
+
+sub read_stack_usage_file {
+ my %su;
+ my $f = shift;
+ open(my $fh, '<', $f)
+ or die "cannot open $f: $!";
+ while (<$fh>) {
+ chomp;
+ my ($file, $func, $size, $type) = split;
+ # Old versions of gcc (at least 4.7) have an annoying quirk in
+ # that a (static) function whose name has been changed into
+ # for example ext4_find_unwritten_pgoff.isra.11 will show up
+ # in the .su file with a name of just "11". Since such a
+ # numeric suffix is likely to change across different
+ # commits/compilers/.configs or whatever else we're trying to
+ # tweak, we can't really track those functions, so we just
+ # silently skip them.
+ #
+ # Newer gcc (at least 5.0) report the full name, so again,
+ # since the suffix is likely to change, we strip it.
+ next if $func =~ m/^[0-9]+$/;
+ $func =~ s/\..*$//;
+ # Line numbers are likely to change; strip those.
+ $file =~ s/:[0-9]+$//;
+ $su{"${file}\t${func}"} = {size => $size, type => $type};
+ }
+ close($fh);
+ return \%su;
+}
+
+@ARGV == 2
+ or die "usage: $0 <old> <new>";
+
+my $old = read_stack_usage_file($ARGV[0]);
+my $new = read_stack_usage_file($ARGV[1]);
+my @common = sort grep {exists $new->{$_}} keys %$old;
+for (@common) {
+ my $x = $old->{$_}{size};
+ my $y = $new->{$_}{size};
+ my $delta = $y - $x;
+ if ($delta) {
+ printf "%s\t%d\t%d\t%+d\n", $_, $x, $y, $delta;
+ }
+}