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Comparing libev/ev.pod (file contents):
Revision 1.139 by root, Wed Apr 2 05:51:40 2008 UTC vs.
Revision 1.142 by root, Sun Apr 6 09:53:18 2008 UTC

… …
358For few fds, this backend is a bit little slower than poll and select, 358For few fds, this backend is a bit little slower than poll and select,
359but it scales phenomenally better. While poll and select usually scale 359but it scales phenomenally better. While poll and select usually scale
360like O(total_fds) where n is the total number of fds (or the highest fd), 360like O(total_fds) where n is the total number of fds (or the highest fd),
361epoll scales either O(1) or O(active_fds). The epoll design has a number 361epoll scales either O(1) or O(active_fds). The epoll design has a number
362of shortcomings, such as silently dropping events in some hard-to-detect 362of shortcomings, such as silently dropping events in some hard-to-detect
363cases and rewiring a syscall per fd change, no fork support and bad 363cases and requiring a syscall per fd change, no fork support and bad
364support for dup. 364support for dup.
365 365
366While stopping, setting and starting an I/O watcher in the same iteration 366While stopping, setting and starting an I/O watcher in the same iteration
367will result in some caching, there is still a syscall per such incident 367will result in some caching, there is still a syscall per such incident
368(because the fd could point to a different file description now), so its 368(because the fd could point to a different file description now), so its
… …
2288 2288
2289This call incurs the overhead of a syscall only once per loop iteration, 2289This call incurs the overhead of a syscall only once per loop iteration,
2290so while the overhead might be noticable, it doesn't apply to repeated 2290so while the overhead might be noticable, it doesn't apply to repeated
2291calls to C<ev_async_send>. 2291calls to C<ev_async_send>.
2292 2292
2293=item bool = ev_async_pending (ev_async *)
2294
2295Returns a non-zero value when C<ev_async_send> has been called on the
2296watcher but the event has not yet been processed (or even noted) by the
2297event loop.
2298
2299C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2300the loop iterates next and checks for the watcher to have become active,
2301it will reset the flag again. C<ev_async_pending> can be used to very
2302quickly check wether invoking the loop might be a good idea.
2303
2304Not that this does I<not> check wether the watcher itself is pending, only
2305wether it has been requested to make this watcher pending.
2306
2293=back 2307=back
2294 2308
2295 2309
2296=head1 OTHER FUNCTIONS 2310=head1 OTHER FUNCTIONS
2297 2311
… …
2723 2737
2724 libev.m4 2738 libev.m4
2725 2739
2726=head2 PREPROCESSOR SYMBOLS/MACROS 2740=head2 PREPROCESSOR SYMBOLS/MACROS
2727 2741
2728Libev can be configured via a variety of preprocessor symbols you have to define 2742Libev can be configured via a variety of preprocessor symbols you have to
2729before including any of its files. The default is not to build for multiplicity 2743define before including any of its files. The default in the absense of
2730and only include the select backend. 2744autoconf is noted for every option.
2731 2745
2732=over 4 2746=over 4
2733 2747
2734=item EV_STANDALONE 2748=item EV_STANDALONE
2735 2749
… …
2761=item EV_USE_NANOSLEEP 2775=item EV_USE_NANOSLEEP
2762 2776
2763If defined to be C<1>, libev will assume that C<nanosleep ()> is available 2777If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2764and will use it for delays. Otherwise it will use C<select ()>. 2778and will use it for delays. Otherwise it will use C<select ()>.
2765 2779
2780=item EV_USE_EVENTFD
2781
2782If defined to be C<1>, then libev will assume that C<eventfd ()> is
2783available and will probe for kernel support at runtime. This will improve
2784C<ev_signal> and C<ev_async> performance and reduce resource consumption.
2785If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
27862.7 or newer, otherwise disabled.
2787
2766=item EV_USE_SELECT 2788=item EV_USE_SELECT
2767 2789
2768If undefined or defined to be C<1>, libev will compile in support for the 2790If undefined or defined to be C<1>, libev will compile in support for the
2769C<select>(2) backend. No attempt at autodetection will be done: if no 2791C<select>(2) backend. No attempt at autodetection will be done: if no
2770other method takes over, select will be it. Otherwise the select backend 2792other method takes over, select will be it. Otherwise the select backend
… …
2806 2828
2807=item EV_USE_EPOLL 2829=item EV_USE_EPOLL
2808 2830
2809If defined to be C<1>, libev will compile in support for the Linux 2831If defined to be C<1>, libev will compile in support for the Linux
2810C<epoll>(7) backend. Its availability will be detected at runtime, 2832C<epoll>(7) backend. Its availability will be detected at runtime,
2811otherwise another method will be used as fallback. This is the 2833otherwise another method will be used as fallback. This is the preferred
2812preferred backend for GNU/Linux systems. 2834backend for GNU/Linux systems. If undefined, it will be enabled if the
2835headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2813 2836
2814=item EV_USE_KQUEUE 2837=item EV_USE_KQUEUE
2815 2838
2816If defined to be C<1>, libev will compile in support for the BSD style 2839If defined to be C<1>, libev will compile in support for the BSD style
2817C<kqueue>(2) backend. Its actual availability will be detected at runtime, 2840C<kqueue>(2) backend. Its actual availability will be detected at runtime,
… …
2836 2859
2837=item EV_USE_INOTIFY 2860=item EV_USE_INOTIFY
2838 2861
2839If defined to be C<1>, libev will compile in support for the Linux inotify 2862If defined to be C<1>, libev will compile in support for the Linux inotify
2840interface to speed up C<ev_stat> watchers. Its actual availability will 2863interface to speed up C<ev_stat> watchers. Its actual availability will
2841be detected at runtime. 2864be detected at runtime. If undefined, it will be enabled if the headers
2865indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2842 2866
2843=item EV_ATOMIC_T 2867=item EV_ATOMIC_T
2844 2868
2845Libev requires an integer type (suitable for storing C<0> or C<1>) whose 2869Libev requires an integer type (suitable for storing C<0> or C<1>) whose
2846access is atomic with respect to other threads or signal contexts. No such 2870access is atomic with respect to other threads or signal contexts. No such

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