[MEDIUM] limit the number of events returned by *poll*
By default, epoll/kqueue used to return as many events as possible.
This could sometimes cause huge latencies (latencies of up to 400 ms
have been observed with many thousands of fds at once). Limiting the
number of events returned also reduces the latency by avoiding too
many blind processing. The value is set to 200 by default and can be
changed in the global section using the tune.maxpollevents parameter.
diff --git a/include/common/defaults.h b/include/common/defaults.h
index cfe60e8..198288f 100644
--- a/include/common/defaults.h
+++ b/include/common/defaults.h
@@ -2,7 +2,7 @@
include/common/defaults.h
Miscellaneous default values.
- Copyright (C) 2000-2006 Willy Tarreau - w@1wt.eu
+ Copyright (C) 2000-2007 Willy Tarreau - w@1wt.eu
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
@@ -78,6 +78,12 @@
#define MIN_RET_FOR_READ_LOOP 1460
#endif
+// the max number of events returned in one call to poll/epoll. Too small a
+// value will cause lots of calls, and too high a value may cause high latency.
+#ifndef MAX_POLL_EVENTS
+#define MAX_POLL_EVENTS 200
+#endif
+
// cookie delimitor in "prefix" mode. This character is inserted between the
// persistence cookie and the original value. The '~' is allowed by RFC2965,
// and should not be too common in server names.