Class: Duffy::System

Inherits:
Object
  • Object
show all
Defined in:
lib/duffy/system.rb

Overview

Depending on your hardware, you may want to make decisions in your code. I use this to figure out how many processes I can launch in parallel.

Class Method Summary collapse

Class Method Details

.cores ⇒ Object

How many actual CPU cores do we have not including Hyperthreading Linux: “cpu cores” in cpuinfo is on a per physical processor basis, so we multiply by the number of CPUs Mac: hw.physicalcpu



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# File 'lib/duffy/system.rb', line 22

def cores
  case RUBY_PLATFORM
    when /linux/  then File.read('/proc/cpuinfo').scan(/(cpu cores).*(\d+)/)[0][1].to_i * cpus
    when /darwin/ then `sysctl -n hw.physicalcpu`.to_i
    else 1
  end
rescue
  1
end

.cpu_percent ⇒ Object

The system’s current CPU utilization. Darwin: Get a list of all processes’ CPU percentage and add them up. Linux: Read /proc/stat twice and take the difference to give cpu time used in that interval.



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# File 'lib/duffy/system.rb', line 52

def cpu_percent
  case RUBY_PLATFORM
    when /darwin/ then `ps -A -o %cpu`.lines.map(&:to_f).inject(:+) / threads
    when /linux/  then proc_diff
    else 0
  end
rescue
  0
end

.cpus ⇒ Object

How many Physical CPUs do you have. Linux: Detected by counting unique physical IDs Mac: hw.packages



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# File 'lib/duffy/system.rb', line 9

def cpus
  case RUBY_PLATFORM
    when /linux/  then File.read('/proc/cpuinfo').scan(/^physical id.*/).uniq.count
    when /darwin/ then `sysctl -n hw.packages`.to_i
    else 1
  end
rescue
  1
end

.mem_available ⇒ Object

Memory available for use in Megabytes Darwin: vm_stat (Pages Free + Pages Inactive) Linux: Read /proc/meminfo



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# File 'lib/duffy/system.rb', line 78

def mem_available
  case RUBY_PLATFORM
    when /darwin/ then `vm_stat`.lines.grep(/(free:|inactive:)\s*(\d+)/){$2}.map(&:to_i).inject(:+) * 4 / 1024
    when /linux/  then File.read("/proc/meminfo").lines.grep(/MemAvail|MemFree/).sort.first.split[1].to_i / 1024
    else 0
  end
rescue
  0
end

.mem_total ⇒ Object

Total system memory in Megabytes Darwin: hw.memsize (bytes) Linux: Read /proc/meminfo



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# File 'lib/duffy/system.rb', line 65

def mem_total
  case RUBY_PLATFORM
    when /darwin/ then `sysctl -n hw.memsize`.to_i / 1024 / 1024
    when /linux/  then File.read("/proc/meminfo").scan(/MemTotal:\s*(\d+)/)[0][0].to_i / 1024
    else 0
  end
rescue
  0
end

.mem_used ⇒ Object

Memory used Subtract mem_available from mem_total. This ignores file cache etc that is not actually used by programs.



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# File 'lib/duffy/system.rb', line 91

def mem_used
  mem_total - mem_available
end

.sane_load ⇒ Object

What is a sane number of threads to use for data processing. Only using physical cores is a waste, using all logical cores decreases performance.



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# File 'lib/duffy/system.rb', line 45

def sane_load
  (cores + threads) / 2
end

.threads ⇒ Object

How many threads does the system have.



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# File 'lib/duffy/system.rb', line 33

def threads
  case RUBY_PLATFORM
    when /linux/  then File.read('/proc/cpuinfo').scan(/^processor\s*:/).size
    when /darwin/ then `sysctl -n hw.ncpu`.to_i
    else 1
  end
rescue
  1
end