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Diffstat (limited to 'erts/doc/src/erl.xml')
| -rw-r--r-- | erts/doc/src/erl.xml | 125 |
1 files changed, 117 insertions, 8 deletions
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml index bb741c7836..77bd952d41 100644 --- a/erts/doc/src/erl.xml +++ b/erts/doc/src/erl.xml @@ -41,6 +41,26 @@ to scroll back to text which has scrolled off the screen. The <c><![CDATA[erl]]></c> program must be used, however, in pipelines or if you want to redirect standard input or output.</p> + <note><p>As of ERTS version 5.8 (OTP-R14A) 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><p> + 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="#+sbt">+sbtu</seealso> command line argument, + or by invoking + <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, + unbound)</seealso>.</p> + </note> </description> <funcs> <func> @@ -521,6 +541,28 @@ <p>Calling <c>erlang:halt/1</c> with a string argument will still produce a crash dump.</p> </item> + <tag><c><![CDATA[+e Number]]></c></tag> + <item> + <p>Set max number of ETS tables.</p> + </item> + <tag><c><![CDATA[+ec]]></c></tag> + <item> + <p>Force the <c>compressed</c> option on all ETS tables. + Only intended for test and evaluation.</p> + </item> + <tag><c><![CDATA[+fnl]]></c></tag> + <item> + <p>The VM works with file names as if they are encoded using the ISO-latin-1 encoding, disallowing Unicode characters with codepoints beyond 255. This is default on operating systems that have transparent file naming, i.e. all Unixes except MacOSX.</p> + </item> + <tag><c><![CDATA[+fnu]]></c></tag> + <item> + <p>The VM works with file names as if they are encoded using UTF-8 (or some other system specific Unicode encoding). This is the default on operating systems that enforce Unicode encoding, i.e. Windows and MacOSX.</p> + <p>By enabling Unicode file name translation on systems where this is not default, you open up to the possibility that some file names can not be interpreted by the VM and therefore will be returned to the program as raw binaries. The option is therefore considered experimental.</p> + </item> + <tag><c><![CDATA[+fna]]></c></tag> + <item> + <p>Selection between <c>+fnl</c> and <c>+fnu</c> is done based on the current locale settings in the OS, meaning that if you have set your terminal for UTF-8 encoding, the filesystem is expected to use the same encoding for filenames (use with care).</p> + </item> <tag><c><![CDATA[+hms Size]]></c></tag> <item> <p>Sets the default heap size of processes to the size @@ -583,6 +625,24 @@ <item> <p>Force ets memory block to be moved on realloc.</p> </item> + <tag><marker id="+rg"><c><![CDATA[+rg ReaderGroupsLimit]]></c></marker></tag> + <item> + <p>Limits the amount of reader groups used by read/write locks + optimized for read operations in the Erlang runtime system. By + default the reader groups limit equals 8.</p> + <p>When the amount of schedulers is less than or equal to the reader + groups limit, each scheduler has its own reader group. When the + amount of schedulers is larger than the reader groups limit, + schedulers share reader groups. Shared reader groups degrades + read lock and read unlock performance while a large amount of + reader groups degrades write lock performance, so the limit is a + tradeoff between performance for read operations and performance + for write operations. Each reader group currently consumes 64 byte + in each read/write lock. Also note that a runtime system using + shared reader groups benefits from <seealso marker="#+sbt">binding + schedulers to logical processors</seealso>, since the reader groups + are distributed better between schedulers.</p> + </item> <tag><marker id="+S"><c><![CDATA[+S Schedulers:SchedulerOnline]]></c></marker></tag> <item> <p>Sets the amount of scheduler threads to create and scheduler @@ -647,8 +707,8 @@ <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, default_bind)</seealso>. </p></item> </taglist> - <p>Binding of schedulers are currently only supported on newer - Linux and Solaris systems.</p> + <p>Binding of schedulers is currently only supported on newer + Linux, Solaris, FreeBSD, and Windows systems.</p> <p>If no CPU topology is available when the <c>+sbt</c> flag is processed and <c>BindType</c> is any other type than <c>u</c>, the runtime system will fail to start. CPU @@ -657,6 +717,22 @@ that the <c>+sct</c> flag may have to be passed before the <c>+sbt</c> flag on the command line (in case no CPU topology has been automatically detected).</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> + <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 advised + to unbind the schedulers using the <c>+sbtu</c> command line + argument, or by invoking + <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, + unbound)</seealso>.</p> <p>For more information, see <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, SchedulerBindType)</seealso>. </p> @@ -777,14 +853,28 @@ <p>For more information, see <seealso marker="erlang#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso>.</p> </item> + <tag><marker id="+swt"><c>+swt very_low|low|medium|high|very_high</c></marker></tag> + <item> + <p>Set scheduler wakeup threshold. Default is <c>medium</c>. + The threshold determines when to wake up sleeping schedulers + when more work than can be handled by currently awake schedulers + exist. A low threshold will cause earlier wakeups, and a high + threshold will cause later wakeups. Early wakeups will + distribute work over multiple schedulers faster, but work will + more easily bounce between schedulers. + </p> + <p><em>NOTE:</em> This flag may be removed or changed at any time + without prior notice. + </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. + Valid range is 4-8192 kilowords. The default stack size + is OS dependent.</p> + </item> </taglist> </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. - Valid range is 4-8192 kilowords. The default stack size - is OS dependent.</p> - </item> <tag><marker id="+t"><c><![CDATA[+t size]]></c></marker></tag> <item> <p>Set the maximum number of atoms the VM can handle. Default is 1048576.</p> @@ -838,6 +928,25 @@ <seealso marker="kernel:error_logger#warning_map/0">error_logger(3)</seealso> for further information.</p> </item> + <tag><c><![CDATA[+zFlag Value]]></c></tag> + <item> + <p>Miscellaneous flags.</p> + <taglist> + <tag><marker id="+zdbbl"><c>+zdbbl size</c></marker></tag> + <item> + <p>Set the distribution buffer busy limit + (<seealso marker="erlang#system_info_dist_buf_busy_limit">dist_buf_busy_limit</seealso>) + in kilobytes. Valid range is 1-2097151. Default is 1024.</p> + <p>A larger buffer limit will allow processes to buffer + more outgoing messages over the distribution. When the + buffer limit has been reached, sending processes will be + suspended until the buffer size has shrunk. The buffer + limit is per distribution channel. A higher limit will + give lower latency and higher throughput at the expense + of higher memory usage.</p> + </item> + </taglist> + </item> </taglist> </section> |