Improve configuration of process and port tables

2 files changed, 75 insertions, 27 deletions

diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 4ef3e089a6..f7d8d37fd3 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -586,13 +586,51 @@
           <seealso marker="erts_alloc">erts_alloc(3)</seealso> for
           further information.</p>
       </item>
+      <tag><c><![CDATA[+n]]></c></tag>
+      <item>
+	<p>Enable synchronous message passing to ports.</p>
+	<p>As of OTP-R16 message passing to ports are truly asynchronously
+	   implemented. Correctly written Erlang programs should be able
+	   to handle this without any issues. Bugs in existing Erlang
+	   programs that make false assumptions about message passing 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 this flag is
+	   deprecated as of its introduction, and is scheduled for removal
+	   in OTP-R17.</p>
+      </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><em>NOTE</em>: It is possible to choose any value in the range
-	  but powers of 2 perform best.</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>
@@ -601,21 +639,14 @@
           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>
@@ -1026,7 +1057,7 @@
           the given number of seconds have elapsed, the emulator will be
           terminated by a SIGALRM signal.</p>
       </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>
@@ -1036,7 +1067,7 @@
           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>
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 0963904b83..2da456d49f 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -3225,10 +3225,11 @@ os_prompt% </pre>
           the owning process using signals of the form
           <c>{'EXIT', Port, PosixCode}</c>. See <c>file(3)</c> for
           possible values of <c>PosixCode</c>.</p>
-        <p><marker id="ERL_MAX_PORTS"></marker>
-          The maximum number of ports that can be open at the same
-          time is 1024 by default, but can be configured by
-          the environment variable <c>ERL_MAX_PORTS</c>.</p>
+	  <p>The maximum number of ports that can be open at the same
+          time can be configured by passing the 
+	  <seealso marker="erl#max_ports"><c>+Q</c></seealso>
+	  command line flag to
+	  <seealso marker="erl"><c>erl(1)</c></seealso>.</p>
       </desc>
     </func>
     <func>
@@ -5955,17 +5956,33 @@ ok
           </item>
           <tag><c>process_count</c></tag>
           <item>
+            <p>Returns the number of ports currently existing at
+              the local node as an integer. The same value as
+              <c>length(erlang:ports())</c> returns.</p>
+          </item>
+          <tag><marker id="system_info_port_limit"><c>port_limit</c></marker></tag>
+          <item>
+            <p>Returns the maximum number of simultaneously existing
+              ports at the local node as an integer. This limit
+              can be configured at startup by using the
+              <seealso marker="erl#max_ports"><c>+Q</c></seealso>
+	      command line flag of
+	      <seealso marker="erl"><c>erl(1)</c></seealso>.</p>
+          </item>
+          <tag><c>process_count</c></tag>
+          <item>
             <p>Returns the number of processes currently existing at
               the local node as an integer. The same value as
               <c>length(processes())</c> returns.</p>
           </item>
-          <tag><c>process_limit</c></tag>
+          <tag><marker id="system_info_process_limit"><c>process_limit</c></marker></tag>
           <item>
-            <p>Returns the maximum number of concurrently existing
+            <p>Returns the maximum number of simultaneously existing
               processes at the local node as an integer. This limit
-              can be configured at startup by using the command line
-              flag <c>+P</c>, see
-              <seealso marker="erts:erl#max_processes">erl(1)</seealso>.</p>
+              can be configured at startup by using the
+              <seealso marker="erl#max_processes"><c>+P</c></seealso>
+	      command line flag of
+	      <seealso marker="erl"><c>erl(1)</c></seealso>.</p>
           </item>
           <tag><c>procs</c></tag>
           <item>