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Marc Alexander Lehmann 14 years ago
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      ev.3
  2. 67
      ev.html

86
ev.3

@ -129,7 +129,7 @@
.\" ========================================================================
.\"
.IX Title ""<STANDARD INPUT>" 1"
.TH "<STANDARD INPUT>" 1 "2007-11-18" "perl v5.8.8" "User Contributed Perl Documentation"
.TH "<STANDARD INPUT>" 1 "2007-11-22" "perl v5.8.8" "User Contributed Perl Documentation"
.SH "NAME"
libev \- a high performance full\-featured event loop written in C
.SH "SYNOPSIS"
@ -262,31 +262,69 @@ or setgid) then libev will \fInot\fR look at the environment variable
override the flags completely if it is found in the environment. This is
useful to try out specific backends to test their performance, or to work
around bugs.
.ie n .IP """EVMETHOD_SELECT"" (portable select backend)" 4
.el .IP "\f(CWEVMETHOD_SELECT\fR (portable select backend)" 4
.IX Item "EVMETHOD_SELECT (portable select backend)"
.PD 0
.ie n .IP """EVMETHOD_POLL"" (poll backend, available everywhere except on windows)" 4
.el .IP "\f(CWEVMETHOD_POLL\fR (poll backend, available everywhere except on windows)" 4
.IX Item "EVMETHOD_POLL (poll backend, available everywhere except on windows)"
.ie n .IP """EVMETHOD_EPOLL"" (linux only)" 4
.el .IP "\f(CWEVMETHOD_EPOLL\fR (linux only)" 4
.IX Item "EVMETHOD_EPOLL (linux only)"
.ie n .IP """EVMETHOD_KQUEUE"" (some bsds only)" 4
.el .IP "\f(CWEVMETHOD_KQUEUE\fR (some bsds only)" 4
.IX Item "EVMETHOD_KQUEUE (some bsds only)"
.ie n .IP """EVMETHOD_DEVPOLL"" (solaris 8 only)" 4
.el .IP "\f(CWEVMETHOD_DEVPOLL\fR (solaris 8 only)" 4
.IX Item "EVMETHOD_DEVPOLL (solaris 8 only)"
.ie n .IP """EVMETHOD_PORT"" (solaris 10 only)" 4
.el .IP "\f(CWEVMETHOD_PORT\fR (solaris 10 only)" 4
.IX Item "EVMETHOD_PORT (solaris 10 only)"
.PD
If one or more of these are ored into the flags value, then only these
backends will be tried (in the reverse order as given here). If one are
specified, any backend will do.
.ie n .IP """EVMETHOD_SELECT"" (value 1, portable select backend)" 4
.el .IP "\f(CWEVMETHOD_SELECT\fR (value 1, portable select backend)" 4
.IX Item "EVMETHOD_SELECT (value 1, portable select backend)"
This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR 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.
.ie n .IP """EVMETHOD_POLL"" (value 2, poll backend, available everywhere except on windows)" 4
.el .IP "\f(CWEVMETHOD_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4
.IX Item "EVMETHOD_POLL (value 2, poll backend, available everywhere except on windows)"
And this is your standard \fIpoll\fR\|(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).
.ie n .IP """EVMETHOD_EPOLL"" (value 4, Linux)" 4
.el .IP "\f(CWEVMETHOD_EPOLL\fR (value 4, Linux)" 4
.IX Item "EVMETHOD_EPOLL (value 4, Linux)"
For few fds, this backend is a bit little slower than poll and select,
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).
.Sp
While stopping and starting an I/O watcher in the same iteration will
result in some caching, there is still a syscall per such incident
(because the fd could point to a different file description now), so its
best to avoid that. Also, \fIdup()\fRed file descriptors might not work very
well if you register events for both fds.
.ie n .IP """EVMETHOD_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
.el .IP "\f(CWEVMETHOD_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
.IX Item "EVMETHOD_KQUEUE (value 8, most BSD clones)"
Kqueue deserves special mention, as at the time of this writing, it
was broken on all BSDs except NetBSD (usually it doesn't work with
anything but sockets and pipes, except on Darwin, where of course its
completely useless). For this reason its not being \*(L"autodetected\*(R" unless
you explicitly specify the flags (i.e. you don't use \s-1EVFLAG_AUTO\s0).
.Sp
It scales in the same way as the epoll backend, but the interface to the
kernel is more efficient (which says nothing about its actual speed, of
course). While starting and stopping an I/O watcher does not cause an
extra syscall as with epoll, it still adds up to four event changes per
incident, so its best to avoid that.
.ie n .IP """EVMETHOD_DEVPOLL"" (value 16, Solaris 8)" 4
.el .IP "\f(CWEVMETHOD_DEVPOLL\fR (value 16, Solaris 8)" 4
.IX Item "EVMETHOD_DEVPOLL (value 16, Solaris 8)"
This is not implemented yet (and might never be).
.ie n .IP """EVMETHOD_PORT"" (value 32, Solaris 10)" 4
.el .IP "\f(CWEVMETHOD_PORT\fR (value 32, Solaris 10)" 4
.IX Item "EVMETHOD_PORT (value 32, Solaris 10)"
This uses the Solaris 10 port mechanism. As with everything on Solaris,
it's really slow, but it still scales very well (O(active_fds)).
.ie n .IP """EVMETHOD_ALL""" 4
.el .IP "\f(CWEVMETHOD_ALL\fR" 4
.IX Item "EVMETHOD_ALL"
Try all backends (even potentially broken ones). Since this is a mask, you
can do stuff like \f(CW\*(C`EVMETHOD_ALL & ~EVMETHOD_KQUEUE\*(C'\fR.
.RE
.RS 4
.Sp
If one or more of these are ored into the flags value, then only these
backends will be tried (in the reverse order as given here). If none are
specified, most compiled-in backend will be tried, usually in reverse
order of their flag values :)
.RE
.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"

67
ev.html

@ -6,7 +6,7 @@
<meta name="description" content="Pod documentation for libev" />
<meta name="inputfile" content="&lt;standard input&gt;" />
<meta name="outputfile" content="&lt;standard output&gt;" />
<meta name="created" content="Sun Nov 18 04:43:20 2007" />
<meta name="created" content="Thu Nov 22 13:26:17 2007" />
<meta name="generator" content="Pod::Xhtml 1.57" />
<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
<body>
@ -188,19 +188,66 @@ override the flags completely if it is found in the environment. This is
useful to try out specific backends to test their performance, or to work
around bugs.</p>
</dd>
<dt><code>EVMETHOD_SELECT</code> (portable select backend)</dt>
<dt><code>EVMETHOD_POLL</code> (poll backend, available everywhere except on windows)</dt>
<dt><code>EVMETHOD_EPOLL</code> (linux only)</dt>
<dt><code>EVMETHOD_KQUEUE</code> (some bsds only)</dt>
<dt><code>EVMETHOD_DEVPOLL</code> (solaris 8 only)</dt>
<dt><code>EVMETHOD_PORT</code> (solaris 10 only)</dt>
<dt><code>EVMETHOD_SELECT</code> (value 1, portable select backend)</dt>
<dd>
<p>If one or more of these are ored into the flags value, then only these
backends will be tried (in the reverse order as given here). If one are
specified, any backend will do.</p>
<p>This is your standard select(2) backend. Not <i>completely</i> 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.</p>
</dd>
<dt><code>EVMETHOD_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt>
<dd>
<p>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).</p>
</dd>
<dt><code>EVMETHOD_EPOLL</code> (value 4, Linux)</dt>
<dd>
<p>For few fds, this backend is a bit little slower than poll and select,
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).</p>
<p>While stopping and starting an I/O watcher in the same iteration will
result in some caching, there is still a syscall per such incident
(because the fd could point to a different file description now), so its
best to avoid that. Also, dup()ed file descriptors might not work very
well if you register events for both fds.</p>
</dd>
<dt><code>EVMETHOD_KQUEUE</code> (value 8, most BSD clones)</dt>
<dd>
<p>Kqueue deserves special mention, as at the time of this writing, it
was broken on all BSDs except NetBSD (usually it doesn't work with
anything but sockets and pipes, except on Darwin, where of course its
completely useless). For this reason its not being &quot;autodetected&quot; unless
you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO).</p>
<p>It scales in the same way as the epoll backend, but the interface to the
kernel is more efficient (which says nothing about its actual speed, of
course). While starting and stopping an I/O watcher does not cause an
extra syscall as with epoll, it still adds up to four event changes per
incident, so its best to avoid that.</p>
</dd>
<dt><code>EVMETHOD_DEVPOLL</code> (value 16, Solaris 8)</dt>
<dd>
<p>This is not implemented yet (and might never be).</p>
</dd>
<dt><code>EVMETHOD_PORT</code> (value 32, Solaris 10)</dt>
<dd>
<p>This uses the Solaris 10 port mechanism. As with everything on Solaris,
it's really slow, but it still scales very well (O(active_fds)).</p>
</dd>
<dt><code>EVMETHOD_ALL</code></dt>
<dd>
<p>Try all backends (even potentially broken ones). Since this is a mask, you
can do stuff like <code>EVMETHOD_ALL &amp; ~EVMETHOD_KQUEUE</code>.</p>
</dd>
</dl>
</p>
<p>If one or more of these are ored into the flags value, then only these
backends will be tried (in the reverse order as given here). If none are
specified, most compiled-in backend will be tried, usually in reverse
order of their flag values :)</p>
</dd>
<dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt>
<dd>

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