--- libev/ev.pod	2007/12/22 11:49:17	1.100
+++ libev/ev.pod	2007/12/23 03:50:10	1.105
@@ -6,7 +6,7 @@
 
   #include <ev.h>
 
-=head1 EXAMPLE PROGRAM
+=head2 EXAMPLE PROGRAM
 
   #include <ev.h>
 
@@ -67,7 +67,7 @@
 details of the event, and then hand it over to libev by I<starting> the
 watcher.
 
-=head1 FEATURES
+=head2 FEATURES
 
 Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
 BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
@@ -84,7 +84,7 @@
 L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
 for example).
 
-=head1 CONVENTIONS
+=head2 CONVENTIONS
 
 Libev is very configurable. In this manual the default configuration will
 be described, which supports multiple event loops. For more info about
@@ -93,7 +93,7 @@
 loops, then all functions taking an initial argument of name C<loop>
 (which is always of type C<struct ev_loop *>) will not have this argument.
 
-=head1 TIME REPRESENTATION
+=head2 TIME REPRESENTATION
 
 Libev represents time as a single floating point number, representing the
 (fractional) number of seconds since the (POSIX) epoch (somewhere near
@@ -308,15 +308,24 @@
 This is your standard select(2) backend. Not I<completely> standard, as
 libev tries to roll its own fd_set with no limits on the number of fds,
 but if that fails, expect a fairly low limit on the number of fds when
-using this backend. It doesn't scale too well (O(highest_fd)), but its usually
-the fastest backend for a low number of fds.
+using this backend. It doesn't scale too well (O(highest_fd)), but its
+usually the fastest backend for a low number of (low-numbered :) fds.
+
+To get good performance out of this backend you need a high amount of
+parallelity (most of the file descriptors should be busy). If you are
+writing a server, you should C<accept ()> in a loop to accept as many
+connections as possible during one iteration. You might also want to have
+a look at C<ev_set_io_collect_interval ()> to increase the amount of
+readyness notifications you get per iteration.
 
 =item C<EVBACKEND_POLL>    (value 2, poll backend, available everywhere except on windows)
 
-And this is your standard poll(2) backend. It's more complicated than
-select, but handles sparse fds better and has no artificial limit on the
-number of fds you can use (except it will slow down considerably with a
-lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
+And this is your standard poll(2) backend. It's more complicated
+than select, but handles sparse fds better and has no artificial
+limit on the number of fds you can use (except it will slow down
+considerably with a lot of inactive fds). It scales similarly to select,
+i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
+performance tips.
 
 =item C<EVBACKEND_EPOLL>   (value 4, Linux)
 
@@ -326,7 +335,7 @@
 epoll scales either O(1) or O(active_fds). The epoll design has a number
 of shortcomings, such as silently dropping events in some hard-to-detect
 cases and rewiring a syscall per fd change, no fork support and bad
-support for dup:
+support for dup.
 
 While stopping, setting and starting an I/O watcher in the same iteration
 will result in some caching, there is still a syscall per such incident
@@ -338,6 +347,13 @@
 need to use non-blocking I/O or other means to avoid blocking when no data
 (or space) is available.
 
+Best performance from this backend is achieved by not unregistering all
+watchers for a file descriptor until it has been closed, if possible, i.e.
+keep at least one watcher active per fd at all times.
+
+While nominally embeddeble in other event loops, this feature is broken in
+all kernel versions tested so far.
+
 =item C<EVBACKEND_KQUEUE>  (value 8, most BSD clones)
 
 Kqueue deserves special mention, as at the time of this writing, it
@@ -359,9 +375,21 @@
 two event changes per incident, support for C<fork ()> is very bad and it
 drops fds silently in similarly hard-to-detect cases.
 
+This backend usually performs well under most conditions.
+
+While nominally embeddable in other event loops, this doesn't work
+everywhere, so you might need to test for this. And since it is broken
+almost everywhere, you should only use it when you have a lot of sockets
+(for which it usually works), by embedding it into another event loop
+(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for
+sockets.
+
 =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
 
-This is not implemented yet (and might never be).
+This is not implemented yet (and might never be, unless you send me an
+implementation). According to reports, C</dev/poll> only supports sockets
+and is not embeddable, which would limit the usefulness of this backend
+immensely.
 
 =item C<EVBACKEND_PORT>    (value 32, Solaris 10)
 
@@ -372,12 +400,19 @@
 notifications, so you need to use non-blocking I/O or other means to avoid
 blocking when no data (or space) is available.
 
+While this backend scales well, it requires one system call per active
+file descriptor per loop iteration. For small and medium numbers of file
+descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
+might perform better.
+
 =item C<EVBACKEND_ALL>
 
 Try all backends (even potentially broken ones that wouldn't be tried
 with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
 C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
 
+It is definitely not recommended to use this flag.
+
 =back
 
 If one or more of these are ored into the flags value, then only these
@@ -601,7 +636,7 @@
 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 bvalue will
+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.
 
 Likewise, by setting a higher I<timeout collect interval> you allow libev
@@ -999,12 +1034,12 @@
 =head3 The special problem of dup'ed file descriptors
 
 Some backends (e.g. epoll), cannot register events for file descriptors,
-but only events for the underlying file descriptions. That menas when you
+but only events for the underlying file descriptions. That means when you
 have C<dup ()>'ed file descriptors and register events for them, only one
 file descriptor might actually receive events.
 
-There is no workaorund possible except not registering events
-for potentially C<dup ()>'ed file descriptors or to resort to
+There is no workaround possible except not registering events
+for potentially C<dup ()>'ed file descriptors, or to resort to
 C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
 
 =head3 The special problem of fork
@@ -2493,7 +2528,7 @@
 
 =item EV_INOTIFY_HASHSIZE
 
-C<ev_staz> watchers use a small hash table to distribute workload by
+C<ev_stat> watchers use a small hash table to distribute workload by
 inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
 usually more than enough. If you need to manage thousands of C<ev_stat>
 watchers you might want to increase this value (I<must> be a power of