[PATCH] Cygwin: Speed up mkimport
Mark Geisert
mark@maxrnd.com
Thu Nov 26 09:56:20 GMT 2020
Cut mkimport elapsed time in half by forking each iteration of the two
time-consuming loops within. Only do this if more than one CPU is
present. In the second loop, combine the two 'objdump' calls into one
system() invocation to avoid a system() invocation per iteration.
---
winsup/cygwin/mkimport | 34 ++++++++++++++++++++++++++--------
1 file changed, 26 insertions(+), 8 deletions(-)
diff --git a/winsup/cygwin/mkimport b/winsup/cygwin/mkimport
index 2b08dfe3d..919dc305b 100755
--- a/winsup/cygwin/mkimport
+++ b/winsup/cygwin/mkimport
@@ -47,6 +47,9 @@ for my $sym (keys %replace) {
$import{$fn} = $imp_sym;
}
+my $ncpus = `grep -c ^processor /proc/cpuinfo`;
+my $forking = $ncpus > 1; # Decides if loops below should fork() each iteration
+
for my $f (keys %text) {
my $imp_sym = delete $import{$f};
my $glob_sym = $text{$f};
@@ -56,25 +59,30 @@ for my $f (keys %text) {
$text{$f} = 0;
} else {
$text{$f} = 1;
- open my $as_fd, '|-', $as, '-o', "$dir/t-$f", "-";
- if ($is64bit) {
- print $as_fd <<EOF;
+ if ($forking && fork) {
+ ; # Testing shows sleep here is unneeded. 'as' runs very quickly.
+ } else {
+ open my $as_fd, '|-', $as, '-o', "$dir/t-$f", "-";
+ if ($is64bit) {
+ print $as_fd <<EOF;
.text
.extern $imp_sym
.global $glob_sym
$glob_sym:
jmp *$imp_sym(%rip)
EOF
- } else {
- print $as_fd <<EOF;
+ } else {
+ print $as_fd <<EOF;
.text
.extern $imp_sym
.global $glob_sym
$glob_sym:
jmp *$imp_sym
EOF
+ }
+ close $as_fd or exit 1;
+ exit 0 if $forking;
}
- close $as_fd or exit 1;
}
}
@@ -86,8 +94,18 @@ for my $f (keys %text) {
if (!$text{$f}) {
unlink $f;
} else {
- system $objcopy, '-R', '.text', $f and exit 1;
- system $objcopy, '-R', '.bss', '-R', '.data', "t-$f" and exit 1;
+ if ($forking && fork) {
+ # Testing shows parent does need to sleep a short time here,
+ # otherwise system is inundated with hundreds of objcopy processes
+ # and the forked perl processes that launched them.
+ my $delay = 0.01; # NOTE: Slower systems may need to raise this
+ select(undef, undef, undef, $delay); # Supports fractional seconds
+ } else {
+ # Do two objcopy calls at once to avoid one system() call overhead
+ system '(', $objcopy, '-R', '.text', $f, ')', '||',
+ $objcopy, '-R', '.bss', '-R', '.data', "t-$f" and exit 1;
+ exit 0 if $forking;
+ }
}
}
--
2.29.2
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