diff options
Diffstat (limited to 'ev.3')
| -rw-r--r-- | ev.3 | 48 |
1 files changed, 46 insertions, 2 deletions
@@ -129,7 +129,7 @@ .\" ======================================================================== .\" .IX Title "EV 1" -.TH EV 1 "2007-12-21" "perl v5.8.8" "User Contributed Perl Documentation" +.TH EV 1 "2007-12-22" "perl v5.8.8" "User Contributed Perl Documentation" .SH "NAME" libev \- a high performance full\-featured event loop written in C .SH "SYNOPSIS" @@ -257,6 +257,11 @@ library in any way. Returns the current time as libev would use it. Please note that the \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp you actually want to know. +.IP "void ev_sleep (ev_tstamp interval)" 4 +.IX Item "void ev_sleep (ev_tstamp interval)" +Sleep for the given interval: The current thread will be blocked until +either it is interrupted or the given time interval has passed. Basically +this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR. .IP "int ev_version_major ()" 4 .IX Item "int ev_version_major ()" .PD 0 @@ -465,7 +470,7 @@ but it scales phenomenally better. While poll and select usually scale like O(total_fds) where n is the total number of fds (or the highest fd), 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 rewuiring a syscall per fd change, no fork support and bad +cases and rewiring a syscall per fd change, no fork support and bad support for dup: .Sp While stopping, setting and starting an I/O watcher in the same iteration @@ -726,6 +731,41 @@ Example: For some weird reason, unregister the above signal handler again. \& ev_ref (loop); \& ev_signal_stop (loop, &exitsig); .Ve +.IP "ev_set_io_collect_interval (ev_tstamp interval)" 4 +.IX Item "ev_set_io_collect_interval (ev_tstamp interval)" +.PD 0 +.IP "ev_set_timeout_collect_interval (ev_tstamp interval)" 4 +.IX Item "ev_set_timeout_collect_interval (ev_tstamp interval)" +.PD +These advanced functions influence the time that libev will spend waiting +for events. Both are by default \f(CW0\fR, meaning that libev will try to +invoke timer/periodic callbacks and I/O callbacks with minimum latency. +.Sp +Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) +allows libev to delay invocation of I/O and timer/periodic callbacks to +increase efficiency of loop iterations. +.Sp +The background is that sometimes your program runs just fast enough to +handle one (or very few) event(s) per loop iteration. While this makes +the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new +events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high +overhead for the actual polling but can deliver many events at once. +.Sp +By setting a higher \fIio collect interval\fR 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 \f(CW\*(C`ev_periodic\*(C'\fR and +\&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. +.Sp +Likewise, by setting a higher \fItimeout collect interval\fR you allow libev +to spend more time collecting timeouts, at the expense of increased +latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers +will not be affected. +.Sp +Many programs can usually benefit by setting the io collect interval to +a value near \f(CW0.1\fR 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 \f(CW0.01\fR, as this approsaches +the timing granularity of most systems. .SH "ANATOMY OF A WATCHER" .IX Header "ANATOMY OF A WATCHER" A watcher is a structure that you create and register to record your @@ -2503,6 +2543,10 @@ runtime if successful). Otherwise no use of the realtime clock option will be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. +.IP "\s-1EV_USE_NANOSLEEP\s0" 4 +.IX Item "EV_USE_NANOSLEEP" +If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available +and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. .IP "\s-1EV_USE_SELECT\s0" 4 .IX Item "EV_USE_SELECT" If undefined or defined to be \f(CW1\fR, libev will compile in support for the |