这是IEx系列五部分中的第一部分, 在这一部分中, 我们将说明如何设置Erlang系统的运行时开关标记

设置Erlang使用的调度器个数

➜  iex --erl "+S 2:2"Erlang/OTP 18 [erts-7.1] [source] [64-bit] [smp:2:2] [async-threads:10] [kernel-poll:false]Interactive Elixir (1.2.1) - press Ctrl+C to exit (type h() ENTER for help)iex(1)>

两个调度器可用, 仅设置一个在线(Online)

➜  iex --erl "+S 2:1"Erlang/OTP 18 [erts-7.1] [source] [64-bit] [smp:2:1] [async-threads:10] [kernel-poll:false]Interactive Elixir (1.2.1) - press Ctrl+C to exit (type h() ENTER for help)iex(1)>

远程Shell

➜  iex --name node1@example.com --remsh node2@example.com

打开内核Poll

➜  iex --erl "+S 2:1 +K true"Erlang/OTP 18 [erts-7.1] [source] [64-bit] [smp:2:1] [async-threads:10] [kernel-poll:true]Interactive Elixir (1.2.1) - press Ctrl+C to exit (type h() ENTER for help)iex(1)>

显示参数列表:

➜ erl +/usr/local/lib/erlang/erts-7.1/bin/beam.smp unknown flag -Usage: beam.smp [flags] [ -- [init_args] ]The flags are:-a size        suggested stack size in kilo words for threads               in the async-thread pool, valid range is [16-8192]-A number      set number of threads in async thread pool,               valid range is [0-1024]-B[c|d|i]      c to have Ctrl-c interrupt the Erlang shell,               d (or no extra option) to disable the break               handler, i to ignore break signals-c bool        enable or disable time correction-C mode        set time warp mode; valid modes are:               no_time_warp|single_time_warp|multi_time_warp-d             don't write a crash dump for internally detected errors               (halt(String) will still produce a crash dump)-fn[u|a|l]     Control how filenames are interpreted-hms size      set minimum heap size in words (default 233)-hmbs size     set minimum binary virtual heap size in words (default 32768)-hpds size     initial process dictionary size (default 10)-K boolean     enable or disable kernel poll-n[s|a|d]      Control behavior of signals to ports               Note that this flag is deprecated!-M
     
     
            memory allocator switches,               see the erts_alloc(3) documentation for more info.-pc 
      
             Control what characters are considered printable (default latin1)-P number      set maximum number of processes on this node,               valid range is [1024-134217727]-Q number      set maximum number of ports on this node,               valid range is [1024-134217727]-R number      set compatibility release number,               valid range [16-18]-r             force ets memory block to be moved on realloc-rg amount     set reader groups limit-sbt type      set scheduler bind type, valid types are:-stbt type     u|ns|ts|ps|s|nnts|nnps|tnnps|db-sbwt val      set scheduler busy wait threshold, valid values are:               none|very_short|short|medium|long|very_long.-scl bool      enable/disable compaction of scheduler load,               see the erl(1) documentation for more info.-sct cput      set cpu topology,               see the erl(1) documentation for more info.-secio bool    enable/disable eager check I/O scheduling,               see the erl(1) documentation for more info.-sub bool      enable/disable scheduler utilization balancing,               see the erl(1) documentation for more info.-sws val       set scheduler wakeup strategy, valid values are:               default|legacy.-swct val      set scheduler wake cleanup threshold, valid values are:               very_lazy|lazy|medium|eager|very_eager.-swt val       set scheduler wakeup threshold, valid values are:               very_low|low|medium|high|very_high.-sss size      suggested stack size in kilo words for scheduler threads,               valid range is [4-8192]-spp Bool      set port parallelism scheduling hint-S n1:n2       set number of schedulers (n1), and number of               schedulers online (n2), maximum for both               numbers is 1024-SP p1:p2      specify schedulers (p1) and schedulers online (p2)               as percentages of logical processors configured and logical               processors available, respectively-t size        set the maximum number of atoms the emulator can handle               valid range is [8192-0]-T number      set modified timing level, valid range is [0-9]-V             print Erlang version-v             turn on chatty mode (GCs will be reported etc)-W
       
              set error logger warnings mapping,               see error_logger documentation for details-zdbbl size    set the distribution buffer busy limit in kilobytes               valid range is [1-2097151]-zdntgc time   set delayed node table gc in seconds               valid values are infinity or intergers in the range [0-100000000]Note that if the emulator is started with erlexec (typicallyfrom the erl script), these flags should be specified with +.