Elixir交互式Shell: 1. 运行时系统标记
Elixir交互式Shell: 2. 常用命令
Elixir交互式Shell: 3. 创建本地和远程Shell
Elixir交互式Shell: 4. 处理文件和脚本
Elixir交互式Shell: 5. 配置IEx

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<X> <Y>      memory allocator switches,
               see the erts_alloc(3) documentation for more info.
-pc <set>      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<i|w|e>      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 (typically
from the erl script), these flags should be specified with +.