aboutsummaryrefslogtreecommitdiffstats
path: root/erts/doc/src/erl.xml
diff options
context:
space:
mode:
Diffstat (limited to 'erts/doc/src/erl.xml')
-rw-r--r--erts/doc/src/erl.xml101
1 files changed, 85 insertions, 16 deletions
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index f931445a3e..99f2466d79 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -582,11 +582,71 @@
<seealso marker="erts_alloc">erts_alloc(3)</seealso> for
further information.</p>
</item>
+ <tag><c><![CDATA[+n Behavior]]></c></tag>
+ <item>
+ <p>Control behavior of signals to ports.</p>
+ <p>As of OTP-R16 signals to ports are truly asynchronously
+ delivered. Note that signals always have been documented as
+ asynchronous. The underlying implementation has, however,
+ previously delivered these signals synchronously. Correctly
+ written Erlang programs should be able to handle this without
+ any issues. Bugs in existing Erlang programs that make false
+ assumptions about signals to ports may, however, be tricky to
+ find. This switch has been introduced in order to at least
+ make it easier to compare behaviors during a transition period.
+ Note that <em>this flag is deprecated</em> as of its
+ introduction, and is scheduled for removal in OTP-R17.
+ <c>Behavior</c> should be one of the following characters:</p>
+ <taglist>
+ <tag><c>d</c></tag>
+ <item>The default. Asynchronous signals. A process that sends
+ a signal to a port may continue execution before the signal
+ has been delivered to the port.</item>
+ <tag><c>s</c></tag>
+ <item>Synchronous signals. A processes that sends a signal
+ to a port will not continue execution until the signal has
+ been delivered. Should <em>only</em> be used for testing and
+ debugging.</item>
+ <tag><c>a</c></tag>
+ <item>Asynchronous signals. As the default, but a processes
+ that sends a signal will even more frequently continue
+ execution before the signal has been delivered to the
+ port. Should <em>only</em> be used for testing and
+ debugging.</item>
+ </taglist>
+ </item>
<tag><marker id="max_processes"><c><![CDATA[+P Number]]></c></marker></tag>
<item>
- <p>Sets the maximum number of concurrent processes for this
- system. <c><![CDATA[Number]]></c> must be in the range 16..134217727.
- Default is 32768.</p>
+ <p>Sets the maximum number of simultaneously existing processes for this
+ system. Valid range for <c>Number</c> is <c>[1024-134217727]</c></p>
+ <p><em>NOTE</em>: The actual maximum chosen may be much larger than
+ the <c>Number</c> passed. Currently the runtime system often,
+ but not always, chooses a value that is a power of 2. This might,
+ however, be changed in the future. The actual value chosen can be
+ checked by calling
+ <seealso marker="erlang#system_info_process_limit">erlang:system_info(process_limit)</seealso>.</p>
+ <p>The default value is <c>262144</c></p>
+ </item>
+ <tag><marker id="max_ports"><c><![CDATA[+Q Number]]></c></marker></tag>
+ <item>
+ <p>Sets the maximum number of simultaneously existing ports for this
+ system. Valid range for <c>Number</c> is <c>[1024-134217727]</c></p>
+ <p><em>NOTE</em>: The actual maximum chosen may be much larger than
+ the actual <c>Number</c> passed. Currently the runtime system often,
+ but not always, chooses a value that is a power of 2. This might,
+ however, be changed in the future. The actual value chosen can be
+ checked by calling
+ <seealso marker="erlang#system_info_port_limit">erlang:system_info(port_limit)</seealso>.</p>
+ <p>The default value used is normally <c>65536</c>. However, if
+ the runtime system is able to determine maximum amount of file
+ descriptors that it is allowed to open and this value is larger
+ than <c>65536</c>, the chosen value will increased to a value
+ larger or equal to the maximum amount of file descriptors that
+ can be opened.</p>
+ <p>Previously the environment variable <c>ERL_MAX_PORTS</c> was used
+ for setting the maximum number of simultaneously existing ports. This
+ environment variable is deprecated, and scheduled for removal in
+ OTP-R17, but can still be used.</p>
</item>
<tag><marker id="compat_rel"><c><![CDATA[+R ReleaseNumber]]></c></marker></tag>
<item>
@@ -595,21 +655,14 @@
default. This flags sets the emulator in compatibility mode
with an earlier Erlang/OTP release <c><![CDATA[ReleaseNumber]]></c>.
The release number must be in the range
- <c><![CDATA[7..<current release>]]></c>. This limits the emulator,
- making it possible for it to communicate with Erlang nodes
- (as well as C- and Java nodes) running that earlier release.</p>
- <p>For example, an R10 node is not automatically compatible
- with an R9 node, but R10 nodes started with the <c><![CDATA[+R 9]]></c>
- flag can co-exist with R9 nodes in the same distributed
- Erlang system, they are R9-compatible.</p>
+ <c><![CDATA[<current release>-2..<current release>]]></c>. This
+ limits the emulator, making it possible for it to communicate
+ with Erlang nodes (as well as C- and Java nodes) running that
+ earlier release.</p>
<p>Note: Make sure all nodes (Erlang-, C-, and Java nodes) of
a distributed Erlang system is of the same Erlang/OTP release,
or from two different Erlang/OTP releases X and Y, where
<em>all</em> Y nodes have compatibility mode X.</p>
- <p>For example: A distributed Erlang system can consist of
- R10 nodes, or of R9 nodes and R9-compatible R10 nodes, but
- not of R9 nodes, R9-compatible R10 nodes and "regular" R10
- nodes, as R9 and "regular" R10 nodes are not compatible.</p>
</item>
<tag><c><![CDATA[+r]]></c></tag>
<item>
@@ -932,6 +985,22 @@
without prior notice.
</p>
</item>
+ <tag><marker id="+spp"><c>+spp Bool</c></marker></tag>
+ <item>
+ <p>Set default scheduler hint for port parallelism. If set to
+ <c>true</c>, the VM will schedule port tasks when it by this can
+ improve the parallelism in the system. If set to <c>false</c>,
+ the VM will try to perform port tasks immediately and by this
+ improve latency at the expense of parallelism. If this
+ flag has not been passed, the default scheduler hint for port
+ parallelism is currently <c>false</c>. The default used can be
+ inspected in runtime by calling
+ <seealso marker="erlang#system_info_port_parallelism">erlang:system_info(port_parallelism)</seealso>.
+ The default can be overriden on port creation by passing the
+ <seealso marker="erlang#open_port_parallelism">parallelism</seealso>
+ option to
+ <seealso marker="erlang#open_port/2">open_port/2</seealso></p>.
+ </item>
<tag><marker id="sched_thread_stack_size"><c><![CDATA[+sss size]]></c></marker></tag>
<item>
<p>Suggested stack size, in kilowords, for scheduler threads.
@@ -1072,7 +1141,7 @@
</item>
</taglist>
</item>
- <tag><c><![CDATA[ERL_AFLAGS]]></c></tag>
+ <tag><marker id="ERL_AFLAGS"><c><![CDATA[ERL_AFLAGS]]></c></marker></tag>
<item>
<p>The content of this environment variable will be added to the
beginning of the command line for <c><![CDATA[erl]]></c>.</p>
@@ -1082,7 +1151,7 @@
the <c><![CDATA[-extra]]></c> section, i.e. the end of the command line
following after an <c><![CDATA[-extra]]></c> flag.</p>
</item>
- <tag><c><![CDATA[ERL_ZFLAGS]]></c> and <c><![CDATA[ERL_FLAGS]]></c></tag>
+ <tag><marker id="ERL_ZFLAGS"><c><![CDATA[ERL_ZFLAGS]]></c></marker> and <marker id="ERL_FLAGS"><c><![CDATA[ERL_FLAGS]]></c></marker></tag>
<item>
<p>The content of these environment variables will be added to the
end of the command line for <c><![CDATA[erl]]></c>.</p>