diff options
author | Christopher Faylor <me@cgf.cx> | 2013-06-08 20:39:52 +0400 |
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committer | Christopher Faylor <me@cgf.cx> | 2013-06-08 20:39:52 +0400 |
commit | 1952976a1b807d0d273de902003c79af0eb4f56c (patch) | |
tree | 3fe8283d3f70338d3f38066767712f7b6ab26cef /winsup/cygwin/miscfuncs.cc | |
parent | 1eaf9215cb27dc368598e5937533411c360fddc9 (diff) |
* miscfuncs.cc (yield): Revert (after researching) to calling SleepEx with 0.
We don't want to actually sleep when calling this function.
Diffstat (limited to 'winsup/cygwin/miscfuncs.cc')
-rw-r--r-- | winsup/cygwin/miscfuncs.cc | 26 |
1 files changed, 11 insertions, 15 deletions
diff --git a/winsup/cygwin/miscfuncs.cc b/winsup/cygwin/miscfuncs.cc index d0748ea6c..819eaa54e 100644 --- a/winsup/cygwin/miscfuncs.cc +++ b/winsup/cygwin/miscfuncs.cc @@ -236,26 +236,22 @@ check_iovec (const struct iovec *iov, int iovcnt, bool forwrite) return (ssize_t) tot; } -/* Try hard to schedule another thread. - - Note: Don't call yield under _cygtls::lock conditions. It results in - potential starvation, especially on a single-CPU system, because - _cygtls::lock also calls yield when waiting for the lock. */ +/* Try hard to schedule another thread. + Remember not to call this in a lock condition or you'll potentially + suffer starvation. */ void yield () { int prio = GetThreadPriority (GetCurrentThread ()); SetThreadPriority (GetCurrentThread (), THREAD_PRIORITY_IDLE); - for (int i = 0; i < 2; i++) - { - /* MSDN implies that SleepEx will force scheduling of other threads. - Unlike SwitchToThread() the documentation does not mention other - cpus so, presumably (hah!), this + using a lower priority will - stall this thread temporarily and cause another to run. - Note: Don't use 0 timeout. This takes a lot of CPU if something - goes wrong. */ - SleepEx (1L, false); - } + /* MSDN implies that SleepEx will force scheduling of other threads. + Unlike SwitchToThread() the documentation does not mention other + cpus so, presumably (hah!), this + using a lower priority will + stall this thread temporarily and cause another to run. + (stackoverflow and others seem to confirm that setting this thread + to a lower priority and calling Sleep with a 0 paramenter will + have this desired effect) */ + Sleep (0L); SetThreadPriority (GetCurrentThread (), prio); } |