https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=aecd8077bfe384a4544e1774d713aff15534d8d4
commit aecd8077bfe384a4544e1774d713aff15534d8d4
Author: Takashi Yano <takashi.y...@nifty.ne.jp>
Date: Thu Dec 12 15:03:39 2024 +0900
Cygwin: signal: Fix high load when retrying to process pending signal
The commit e10f822a2b39 has a problem that CPU load gets high if
pending signal is not processed successfully for a long time.
With this patch, wait_sig() calls Sleep(1), rather than yield(),
if the pending signal has not been processed successfully for a
predetermined time to prevent CPU from high load.
Addresses: https://cygwin.com/pipermail/cygwin/2024-December/256884.html
Fixes: e10f822a2b39 ("Cygwin: signal: Handle queued signal without explicit
__SIGFLUSH")
Reported-by: 凯夏 <walke...@gmail.com>
Reviewed-by: Corinna Vinschen <cori...@vinschen.de>
Signed-off-by: Takashi Yano <takashi.y...@nifty.ne.jp>
(cherry picked from commit 1d1451ccd2a6c0f0146ddee68f386061b69863c0)
Diff:
---
winsup/cygwin/sigproc.cc | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc
index 1ab33fc3c..58a9e5a31 100644
--- a/winsup/cygwin/sigproc.cc
+++ b/winsup/cygwin/sigproc.cc
@@ -1346,6 +1346,13 @@ wait_sig (VOID *)
hntdll = GetModuleHandle ("ntdll.dll");
SetThreadPriority (GetCurrentThread (), THREAD_PRIORITY_NORMAL);
+
+ /* GetTickCount() here is enough because GetTickCount() - t0 does
+ not overflow until 49 days psss. Even if GetTickCount() overflows,
+ GetTickCount() - t0 returns correct value, since underflow in
+ unsigned wraps correctly. Pending a signal for more thtn 49
+ days would be noncense. */
+ DWORD t0 = GetTickCount ();
for (;;)
{
DWORD nb;
@@ -1355,7 +1362,7 @@ wait_sig (VOID *)
else if (sigq.start.next
&& PeekNamedPipe (my_readsig, NULL, 0, NULL, &nb, NULL) && !nb)
{
- yield ();
+ Sleep (GetTickCount () - t0 > 10 ? 1 : 0);
pack.si.si_signo = __SIGFLUSH;
}
else if (!ReadFile (my_readsig, &pack, sizeof (pack), &nb, NULL))
@@ -1365,6 +1372,8 @@ wait_sig (VOID *)
system_printf ("garbled signal pipe data nb %u, sig %d", nb,
pack.si.si_signo);
continue;
}
+ if (pack.si.si_signo != __SIGFLUSH)
+ t0 = GetTickCount ();
sigq.retry = false;
/* Don't process signals when we start exiting */
