From eefc9a09a2ead1bab1ec265a158ea4250535d44e Mon Sep 17 00:00:00 2001
From: root <root>
Date: Tue, 30 Jun 2009 06:24:38 +0000
Subject: *** empty log message ***

---
 ev.pod | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

(limited to 'ev.pod')

diff --git a/ev.pod b/ev.pod
index d2de446..3e4c94a 100644
--- a/ev.pod
+++ b/ev.pod
@@ -813,7 +813,9 @@ By setting a higher I<io collect interval> you allow libev to spend more
 time collecting I/O events, so you can handle more events per iteration,
 at the cost of increasing latency. Timeouts (both C<ev_periodic> and
 C<ev_timer>) will be not affected. Setting this to a non-null value will
-introduce an additional C<ev_sleep ()> call into most loop iterations.
+introduce an additional C<ev_sleep ()> call into most loop iterations. The
+sleep time ensures that libev will not poll for I/O events more often then
+once per this interval, on average.
 
 Likewise, by setting a higher I<timeout collect interval> you allow libev
 to spend more time collecting timeouts, at the expense of increased
@@ -825,7 +827,11 @@ Many (busy) programs can usually benefit by setting the I/O collect
 interval to a value near C<0.1> or so, which is often enough for
 interactive servers (of course not for games), likewise for timeouts. It
 usually doesn't make much sense to set it to a lower value than C<0.01>,
-as this approaches the timing granularity of most systems.
+as this approaches the timing granularity of most systems. Note that if
+you do transactions with the outside world and you can't increase the
+parallelity, then this setting will limit your transaction rate (if you
+need to poll once per transaction and the I/O collect interval is 0.01,
+then you can't do more than 100 transations per second).
 
 Setting the I<timeout collect interval> can improve the opportunity for
 saving power, as the program will "bundle" timer callback invocations that
@@ -834,6 +840,12 @@ times the process sleeps and wakes up again. Another useful technique to
 reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
 they fire on, say, one-second boundaries only.
 
+Example: we only need 0.1s timeout granularity, and we wish not to poll
+more often than 100 times per second:
+
+   ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1);
+   ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
+
 =item ev_loop_verify (loop)
 
 This function only does something when C<EV_VERIFY> support has been
-- 
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