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* [newlib-cygwin] Cygwin: sigproc: Eliminate redundant copying of chld_procs
@ 2020-08-28 17:38 Corinna Vinschen
0 siblings, 0 replies; only message in thread
From: Corinna Vinschen @ 2020-08-28 17:38 UTC (permalink / raw)
To: cygwin-cvs
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=b05b0b78fa91514473b092877da0f13be5a6b2c5
commit b05b0b78fa91514473b092877da0f13be5a6b2c5
Author: Corinna Vinschen <corinna@vinschen.de>
Date: Fri Aug 28 19:34:52 2020 +0200
Cygwin: sigproc: Eliminate redundant copying of chld_procs
On PROC_EXEC_CLEANUP, the pinfo's in chld_procs are removed.
This is done in a loop always removing the child with index 0.
This, however, results in copying the last child's pinfo in
chld_procs to position 0. Do this for 100 children and you
get 99 entirely useless copy operations.
Fix this by calling remove_proc in reverse order.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Diff:
---
winsup/cygwin/sigproc.cc | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc
index f46d3d0d8..aa946fb4c 100644
--- a/winsup/cygwin/sigproc.cc
+++ b/winsup/cygwin/sigproc.cc
@@ -299,8 +299,10 @@ proc_subproc (DWORD what, uintptr_t val)
goto scan_wait;
case PROC_EXEC_CLEANUP:
+ /* Cleanup backwards to eliminate redundant copying of chld_procs
+ array members inside remove_proc. */
while (chld_procs.count ())
- remove_proc (0);
+ remove_proc (chld_procs.count () - 1);
for (w = &waitq_head; w->next != NULL; w = w->next)
CloseHandle (w->next->ev);
break;
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2020-08-28 17:38 [newlib-cygwin] Cygwin: sigproc: Eliminate redundant copying of chld_procs Corinna Vinschen
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