--- libev/ev.pod	2007/12/07 18:09:43	1.68
+++ libev/ev.pod	2007/12/07 19:15:39	1.69
@@ -50,6 +50,10 @@
 
 =head1 DESCRIPTION
 
+The newest version of this document is also available as a html-formatted
+web page you might find easier to navigate when reading it for the first
+time: L<http://cvs.schmorp.de/libev/ev.html>.
+
 Libev is an event loop: you register interest in certain events (such as a
 file descriptor being readable or a timeout occuring), and it will manage
 these event sources and provide your program with events.
@@ -2125,6 +2129,23 @@
 for multiple event loops and there is no first event loop pointer
 argument. Instead, all functions act on the single default loop.
 
+=item EV_MINPRI
+
+=item EV_MAXPRI
+
+The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
+C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
+provide for more priorities by overriding those symbols (usually defined
+to be C<-2> and C<2>, respectively).
+
+When doing priority-based operations, libev usually has to linearly search
+all the priorities, so having many of them (hundreds) uses a lot of space
+and time, so using the defaults of five priorities (-2 .. +2) is usually
+fine.
+
+If your embedding app does not need any priorities, defining these both to
+C<0> will save some memory and cpu.
+
 =item EV_PERIODIC_ENABLE
 
 If undefined or defined to be C<1>, then periodic timers are supported. If
@@ -2240,20 +2261,45 @@
 
 =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
 
+This means that, when you have a watcher that triggers in one hour and
+there are 100 watchers that would trigger before that then inserting will
+have to skip those 100 watchers.
+
 =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
 
+That means that for changing a timer costs less than removing/adding them
+as only the relative motion in the event queue has to be paid for.
+
 =item Starting io/check/prepare/idle/signal/child watchers: O(1)
 
+These just add the watcher into an array or at the head of a list. If
+the array needs to be extended libev needs to realloc and move the whole
+array, but this happen asymptotically less and less with more watchers,
+thus amortised O(1).
+
 =item Stopping check/prepare/idle watchers: O(1)
 
 =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
 
+These watchers are stored in lists then need to be walked to find the
+correct watcher to remove. The lists are usually short (you don't usually
+have many watchers waiting for the same fd or signal).
+
 =item Finding the next timer per loop iteration: O(1)
 
 =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
 
+A change means an I/O watcher gets started or stopped, which requires
+libev to recalculate its status (and possibly tell the kernel).
+
 =item Activating one watcher: O(1)
 
+=item Priority handling: O(number_of_priorities)
+
+Priorities are implemented by allocating some space for each
+priority. When doing priority-based operations, libev usually has to
+linearly search all the priorities.
+
 =back