diff options
Diffstat (limited to 'erts/doc/src/erlang.xml')
| -rw-r--r-- | erts/doc/src/erlang.xml | 225 |
1 files changed, 118 insertions, 107 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index b923a5f1fc..fbe7b36163 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2011</year> + <year>1996</year><year>2012</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -215,9 +215,9 @@ representation of <c>Atom</c>. If <c>Encoding</c> is <c>latin1</c>, there will be one byte for each character in the text representation. If <c>Encoding</c> is <c>utf8</c> or - <c>unicode</c>, the characters will encoded using UTF-8 + <c>unicode</c>, the characters will be encoded using UTF-8 (meaning that characters from 16#80 up to 0xFF will be - encode in two bytes).</p> + encoded in two bytes).</p> <note><p>Currently, <c>atom_to_binary(Atom, latin1)</c> can never fail because the text representation of an atom can only contain @@ -268,7 +268,7 @@ <p>If <c>PosLen</c> in any way references outside the binary, a <c>badarg</c> exception is raised.</p> - <p><c>Start</c> is zero-based, i.e:</p> + <p><c>Start</c> is zero-based, i.e.:</p> <code> 1> Bin = <<1,2,3>> 2> binary_part(Bin,{0,2}). @@ -724,9 +724,12 @@ false</pre> size limit.</p> </item> <tag><c>{line_length, integer()}</c></tag> - <item><p>Applies only to line oriented protocols - (<c>line</c>, <c>http</c>). Lines longer than this - will be truncated.</p> + <item><p>For packet type <c>line</c>, truncate lines longer + than the indicated length.</p> + <p>Option <c>line_length</c> also applies to <c>http*</c> + packet types as an alias for option <c>packet_size</c> in the + case when <c>packet_size</c> itself is not set. This usage is + only intended for backward compatibility.</p> </item> </taglist> <pre> @@ -770,9 +773,9 @@ false</pre> turned off, nothing happens.</p> <p>Once <c>demonitor(MonitorRef)</c> has returned it is guaranteed that no <c>{'DOWN', MonitorRef, _, _, _}</c> message - due to the monitor will be placed in the callers message queue + due to the monitor will be placed in the caller's message queue in the future. A <c>{'DOWN', MonitorRef, _, _, _}</c> message - might have been placed in the callers message queue prior to + might have been placed in the caller's message queue prior to the call, though. Therefore, in most cases, it is advisable to remove such a <c>'DOWN'</c> message from the message queue after monitoring has been stopped. @@ -815,7 +818,7 @@ false</pre> <tag><c>flush</c></tag> <item> <p>Remove (one) <c>{_, MonitorRef, _, _, _}</c> message, - if there is one, from the callers message queue after + if there is one, from the caller's message queue after monitoring has been stopped.</p> <p>Calling <c>demonitor(MonitorRef, [flush])</c> is equivalent to the following, but more efficient:</p> @@ -844,7 +847,7 @@ false</pre> <item><p>The monitor was not found and could not be removed. This probably because someone already has placed a <c>'DOWN'</c> message corresponding to this monitor - in the callers message queue. + in the caller's message queue. </p> </item> </taglist> @@ -2866,7 +2869,7 @@ os_prompt%</pre> <p>For external programs, the <c>PATH</c> is searched (or an equivalent method is used to find programs, depending on operating system). This is done by invoking - the shell och certain platforms. The first space + the shell on certain platforms. The first space separated token of the command will be considered as the name of the executable (or driver). This (among other things) makes this option unsuitable for running @@ -3719,12 +3722,6 @@ os_prompt%</pre> <tag><c>process_flag(save_calls, N)</c></tag> <item> - <p>When there are runnable processes on priority <c>max</c> - no processes on priority <c>low</c>, <c>normal</c>, or - <c>high</c> will be selected for execution. As with the - <c>high</c> priority, processes on lower priorities might - execute in parallel with processes on priority <c>max</c>. - </p> <p><c>N</c> must be an integer in the interval 0..10000. If <c>N</c> > 0, call saving is made active for the process, which means that information about the <c>N</c> @@ -3912,7 +3909,7 @@ os_prompt%</pre> <item> <p>Return the current call stack back-trace (<em>stacktrace</em>) of the process. The stack has the same format as returned by - <seealso marker="#get_stacktrace/1">erlang:get_stacktrace/0</seealso>. + <seealso marker="#get_stacktrace/0">erlang:get_stacktrace/0</seealso>. </p> </item> <tag><c>{dictionary, Dictionary}</c></tag> @@ -4936,6 +4933,21 @@ true</pre> threads in the Erlang run-time system and may therefore be greater than the wall-clock time.</p> </item> + <tag><marker id="statistics_scheduler_wall_time"><c>scheduler_wall_time</c></marker></tag> + <item> + <p>Returns + <c>[{Scheduler_Id, Scheduler_Worked_Time, Scheduler_Total_Time}]</c>, time lapses are since the + the system flag <seealso marker="#system_flag_scheduler_wall_time">scheduler_wall_time</seealso> + was set to true. + Returns <c>undefined</c> if the system flag <seealso marker="#system_flag_scheduler_wall_time"> + scheduler_wall_time</seealso> is set to false. + </p> + <p>The list of scheduler information is unsorted and may come in different order + between calls. The time unit is undefined and may be changed and should only be used + to calculate relative utilization. + </p> + </item> + <tag><c>wall_clock</c></tag> <item> <p>Returns @@ -5075,6 +5087,14 @@ true</pre> <v>Flag, Value, OldValue -- see below</v> </type> <desc> + <warning> + <p>The + <seealso marker="#system_flag_cpu_topology">cpu_topology</seealso>, + and + <seealso marker="#system_flag_scheduler_bind_type">scheduler_bind_type</seealso> + <c>Flag</c>s are <em>deprecated</em> and have been scheduled for + removal in erts-5.10/OTP-R16.</p> + </warning> <p>Sets various system properties of the Erlang node. Returns the old value of the flag.</p> <taglist> @@ -5085,6 +5105,12 @@ true</pre> </item> <tag><marker id="system_flag_cpu_topology"><c>erlang:system_flag(cpu_topology, CpuTopology)</c></marker></tag> <item> + <p><em>NOTE:</em> This argument is <em>deprecated</em> and + scheduled for removal in erts-5.10/OTP-R16. Instead of using + this argument you are advised to use the <c>erl</c> command + line argument <seealso marker="erts:erl#+sct">+sct</seealso>. + When this argument has been removed a final CPU topology to use + will be determined at emulator boot time.</p> <p>Sets the user defined <c>CpuTopology</c>. The user defined CPU topology will override any automatically detected CPU topology. By passing <c>undefined</c> as <c>CpuTopology</c> @@ -5099,15 +5125,15 @@ true</pre> to rebind according to the new CPU topology. </p> <p>The user defined CPU topology can also be set by passing - the <seealso marker="erl#+sct">+sct</seealso> command + the <seealso marker="erts:erl#+sct">+sct</seealso> command line argument to <c>erl</c>. </p> <p>For information on the <c>CpuTopology</c> type and more, see the documentation of <seealso marker="#system_info_cpu_topology">erlang:system_info(cpu_topology)</seealso>, - the <c>erl</c> <seealso marker="erl#+sct">+sct</seealso> - emulator flag, and - <seealso marker="#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, How)</seealso>. + and the <c>erl</c> <seealso marker="erts:erl#+sct">+sct</seealso> + and <seealso marker="erts:erl#+sbt">+sbt</seealso> + command line flags. </p> </item> <tag><c>erlang:system_flag(fullsweep_after, Number)</c></tag> @@ -5183,6 +5209,12 @@ true</pre> </item> <tag><marker id="system_flag_scheduler_bind_type"><c>erlang:system_flag(scheduler_bind_type, How)</c></marker></tag> <item> + <p><em>NOTE:</em> This argument is <em>deprecated</em> and + scheduled for removal in erts-5.10/OTP-R16. Instead of using + this argument you are advised to use the <c>erl</c> command + line argument <seealso marker="erts:erl#+sbt">+sbt</seealso>. + When this argument has been removed a final scheduler bind type + to use will be determined at emulator boot time.</p> <p>Controls if and how schedulers are bound to logical processors.</p> <p>When <c>erlang:system_flag(scheduler_bind_type, How)</c> is @@ -5204,93 +5236,61 @@ true</pre> the CPU topology needs to be known. If the runtime system fails to automatically detect the CPU topology, it can be defined. For more information on how to define the CPU topology, see - <seealso marker="#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso>. + the <c>erl</c> <seealso marker="erts:erl#+sct">+sct</seealso> command + line flag. </p> - <p>The runtime system will by default bind schedulers to logical - processors using the <c>default_bind</c> bind type if the amount - of schedulers are at least equal to the amount of logical - processors configured, binding of schedulers is supported, - and a CPU topology is available at startup. + <p>The runtime system will by default <em>not</em> bind schedulers + to logical processors. </p> <p><em>NOTE:</em> If the Erlang runtime system is the only operating system process that binds threads to logical processors, this improves the performance of the runtime system. However, if other operating system processes (as for example another Erlang runtime system) also bind threads to logical processors, there - might be a performance penalty instead. If this is the case you, - are are advised to unbind the schedulers using the - <seealso marker="erl#+sbt">+sbtu</seealso> command line argument, - or <c>erlang:system_flag(scheduler_bind_type, unbound)</c>.</p> + might be a performance penalty instead. In some cases this + performance penalty might be severe. If this is the case, you + are advised to not bind the schedulers.</p> <p>Schedulers can be bound in different ways. The <c>How</c> argument determines how schedulers are bound. <c>How</c> can currently be one of:</p> <taglist> <tag><c>unbound</c></tag> - <item> - <p>Schedulers will not be bound to logical processors, i.e., - the operating system decides where the scheduler threads - execute, and when to migrate them. This is the default.</p> - </item> + <item><p>Same as the <c>erl</c> command line argument + <seealso marker="erts:erl#+sbt">+sbt u</seealso>. + </p></item> <tag><c>no_spread</c></tag> - <item> - <p>Schedulers with close scheduler identifiers will be bound - as close as possible in hardware.</p> - </item> + <item><p>Same as the <c>erl</c> command line argument + <seealso marker="erts:erl#+sbt">+sbt ns</seealso>. + </p></item> <tag><c>thread_spread</c></tag> - <item> - <p>Thread refers to hardware threads (e.g. Intels - hyper-threads). Schedulers with low scheduler identifiers, - will be bound to the first hardware thread of each core, - then schedulers with higher scheduler identifiers will be - bound to the second hardware thread of each core, etc.</p> - </item> + <item><p>Same as the <c>erl</c> command line argument + <seealso marker="erts:erl#+sbt">+sbt ts</seealso>. + </p></item> <tag><c>processor_spread</c></tag> - <item> - <p>Schedulers will be spread like <c>thread_spread</c>, but - also over physical processor chips.</p> - </item> + <item><p>Same as the <c>erl</c> command line argument + <seealso marker="erts:erl#+sbt">+sbt ps</seealso>. + </p></item> <tag><c>spread</c></tag> - <item> - <p>Schedulers will be spread as much as possible.</p> - </item> + <item><p>Same as the <c>erl</c> command line argument + <seealso marker="erts:erl#+sbt">+sbt s</seealso>. + </p></item> <tag><c>no_node_thread_spread</c></tag> - <item> - <p>Like <c>thread_spread</c>, but if multiple NUMA - (Non-Uniform Memory Access) nodes exists, - schedulers will be spread over one NUMA node at a time, - i.e., all logical processors of one NUMA node will - be bound to schedulers in sequence.</p> - </item> + <item><p>Same as the <c>erl</c> command line argument + <seealso marker="erts:erl#+sbt">+sbt nnts</seealso>. + </p></item> <tag><c>no_node_processor_spread</c></tag> - <item> - <p>Like <c>processor_spread</c>, but if multiple NUMA - nodes exists, schedulers will be spread over one - NUMA node at a time, i.e., all logical processors of - one NUMA node will be bound to schedulers in sequence.</p> - </item> + <item><p>Same as the <c>erl</c> command line argument + <seealso marker="erts:erl#+sbt">+sbt nnps</seealso>. + </p></item> <tag><c>thread_no_node_processor_spread</c></tag> - <item> - <p>A combination of <c>thread_spread</c>, and - <c>no_node_processor_spread</c>. Schedulers will be - spread over hardware threads across NUMA nodes, but - schedulers will only be spread over processors internally - in one NUMA node at a time.</p> - </item> + <item><p>Same as the <c>erl</c> command line argument + <seealso marker="erts:erl#+sbt">+sbt tnnps</seealso>. + </p></item> <tag><c>default_bind</c></tag> - <item> - <p>Binds schedulers the default way. Currently the default - is <c>thread_no_node_processor_spread</c> (which might change - in the future).</p> - </item> + <item><p>Same as the <c>erl</c> command line argument + <seealso marker="erts:erl#+sbt">+sbt db</seealso>. + </p></item> </taglist> - <p>How schedulers are bound matters. For example, in - situations when there are fewer running processes than - schedulers online, the runtime system tries to migrate - processes to schedulers with low scheduler identifiers. - The more the schedulers are spread over the hardware, - the more resources will be available to the runtime - system in such situations. - </p> <p>The value returned equals <c>How</c> before the <c>scheduler_bind_type</c> flag was changed.</p> <p>Failure:</p> @@ -5309,17 +5309,25 @@ true</pre> </item> </taglist> <p>The scheduler bind type can also be set by passing - the <seealso marker="erl#+sbt">+sbt</seealso> command + the <seealso marker="erts:erl#+sbt">+sbt</seealso> command line argument to <c>erl</c>. </p> <p>For more information, see <seealso marker="#system_info_scheduler_bind_type">erlang:system_info(scheduler_bind_type)</seealso>, <seealso marker="#system_info_scheduler_bindings">erlang:system_info(scheduler_bindings)</seealso>, - the <c>erl</c> <seealso marker="erl#+sbt">+sbt</seealso> - emulator flag, and - <seealso marker="#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso>. + the <c>erl</c> <seealso marker="erts:erl#+sbt">+sbt</seealso> + and <seealso marker="erts:erl#+sct">+sct</seealso> command line + flags. </p> </item> + <tag><marker id="system_flag_scheduler_wall_time"><c>erlang:system_flag(scheduler_wall_time, Boolean)</c></marker></tag> + <item> + <p>Turns on/off scheduler wall time measurements. </p> + <p>For more information see, + <seealso marker="#statistics_scheduler_wall_time">erlang:statistics(scheduler_wall_time)</seealso>. + </p> + </item> + <tag><marker id="system_flag_schedulers_online"><c>erlang:system_flag(schedulers_online, SchedulersOnline)</c></marker></tag> <item> <p>Sets the amount of schedulers online. Valid range is @@ -5331,6 +5339,7 @@ true</pre> <seealso marker="#system_info_schedulers_online">erlang:system_info(schedulers_online)</seealso>. </p> </item> + <tag><c>erlang:system_flag(trace_control_word, TCW)</c></tag> <item> <p>Sets the value of the node's trace control word to @@ -5518,10 +5527,12 @@ true</pre> <item> <p>Returns the <c>CpuTopology</c> which currently is used by the emulator. The CPU topology is used when binding schedulers - to logical processors. The CPU topology used is the user defined - CPU topology if such exist; otherwise, the automatically - detected CPU topology if such exist. If no CPU topology - exist <c>undefined</c> is returned.</p> + to logical processors. The CPU topology used is the + <seealso marker="erlang#system_info_cpu_topology_defined">user + defined CPU topology</seealso> if such exists; otherwise, the + <seealso marker="erlang#system_info_cpu_topology_detected">automatically + detected CPU topology</seealso> if such exists. If no CPU topology + exists, <c>undefined</c> is returned.</p> <p>Types:</p> <list type="bulleted"> <item><c>CpuTopology = LevelEntryList | undefined</c></item> @@ -5568,8 +5579,8 @@ true</pre> <item> <p>Returns the user defined <c>CpuTopology</c>. For more information see the documentation of - <seealso marker="#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso> - and the documentation of the + the <c>erl</c> <seealso marker="erts:erl#+sct">+sct</seealso> command + line flag, and the documentation of the <seealso marker="#system_info_cpu_topology">cpu_topology</seealso> argument. </p> @@ -5647,7 +5658,7 @@ true</pre> <item> <p>Returns the value of the distribution buffer busy limit in bytes. This limit can be set on startup by passing the - <seealso marker="erl#+zdbbl">+zdbbl</seealso> command line + <seealso marker="erts:erl#+zdbbl">+zdbbl</seealso> command line flag to <c>erl</c>.</p> </item> <tag><c>fullsweep_after</c></tag> @@ -5849,14 +5860,13 @@ true</pre> <p>Returns information on how user has requested schedulers to be bound or not bound.</p> <p><em>NOTE:</em> Even though user has requested - schedulers to be bound via - <seealso marker="#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, How)</seealso>, - they might have silently failed to bind. In order to - inspect actual scheduler bindings call + schedulers to be bound, they might have silently failed + to bind. In order to inspect actual scheduler bindings call <seealso marker="#system_info_scheduler_bindings">erlang:system_info(scheduler_bindings)</seealso>. </p> <p>For more information, see - <seealso marker="#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, How)</seealso>, and + the <c>erl</c> <seealso marker="erts:erl#+sbt">+sbt</seealso> + command line argument, and <seealso marker="#system_info_scheduler_bindings">erlang:system_info(scheduler_bindings)</seealso>. </p> </item> @@ -5879,7 +5889,8 @@ true</pre> <p>Note that only schedulers online can be bound to logical processors.</p> <p>For more information, see - <seealso marker="#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, How)</seealso>, + the <c>erl</c> <seealso marker="erts:erl#+sbt">+sbt</seealso> + command line argument, <seealso marker="#system_info_schedulers_online">erlang:system_info(schedulers_online)</seealso>. </p> </item> @@ -7103,7 +7114,7 @@ true</pre> <c>Id</c> has no effect on the caller in the future (unless the link is setup again). If caller is trapping exits, an <c>{'EXIT', Id, _}</c> message due to the link might have - been placed in the callers message queue prior to the call, + been placed in the caller's message queue prior to the call, though. Note, the <c>{'EXIT', Id, _}</c> message can be the result of the link, but can also be the result of <c>Id</c> calling <c>exit/2</c>. Therefore, it <em>may</em> be |