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Fix condition in select which results in busy loop. 

The check for current timestamp > start timestamp has an unwelcome
side effect:  The loop is not left as long as the current timestamp
hasn't been incremented.  This leads to busy loops of about one tick
(10 to 16 ms per MSDN).

This fixes https://cygwin.com/ml/cygwin/2016-05/msg00327.html

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2016-06-06 16:18:53 +02:00
parent 7239bb7b3d
commit 83834110a0
1 changed files with 1 additions and 1 deletions
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winsup/cygwin/select.cc
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@ -211,7 +211,7 @@ select (int maxfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
{ {
select_printf ("recalculating us"); select_printf ("recalculating us");
LONGLONG now = gtod.usecs (); LONGLONG now = gtod.usecs ();
if (now > (start_time + us)) if (now >= (start_time + us))
{ {
select_printf ("timed out after verification"); select_printf ("timed out after verification");
/* Set descriptor bits to zero per POSIX. */ /* Set descriptor bits to zero per POSIX. */