diff --git a/lib/concurrent-ruby/concurrent/utility/processor_counter.rb b/lib/concurrent-ruby/concurrent/utility/processor_counter.rb index 007668ae6..2dd91b59a 100644 --- a/lib/concurrent-ruby/concurrent/utility/processor_counter.rb +++ b/lib/concurrent-ruby/concurrent/utility/processor_counter.rb @@ -12,6 +12,7 @@ def initialize @processor_count = Delay.new { compute_processor_count } @physical_processor_count = Delay.new { compute_physical_processor_count } @cpu_quota = Delay.new { compute_cpu_quota } + @cpu_shares = Delay.new { compute_cpu_shares } end def processor_count @@ -41,6 +42,10 @@ def cpu_quota @cpu_quota.value end + def cpu_shares + @cpu_shares.value + end + private def compute_processor_count @@ -113,6 +118,20 @@ def compute_cpu_quota end end end + + def compute_cpu_shares + if RbConfig::CONFIG["target_os"].include?("linux") + if File.exist?("/sys/fs/cgroup/cpu.weight") + # cgroups v2: https://docs.kernel.org/admin-guide/cgroup-v2.html#cpu-interface-files + # Ref: https://github.com/kubernetes/enhancements/tree/master/keps/sig-node/2254-cgroup-v2#phase-1-convert-from-cgroups-v1-settings-to-v2 + weight = File.read("/sys/fs/cgroup/cpu.weight").to_f + ((((weight - 1) * 262142) / 9999) + 2) / 1024 + elsif File.exist?("/sys/fs/cgroup/cpu/cpu.shares") + # cgroups v1: https://kernel.googlesource.com/pub/scm/linux/kernel/git/glommer/memcg/+/cpu_stat/Documentation/cgroups/cpu.txt + File.read("/sys/fs/cgroup/cpu/cpu.shares").to_f / 1024 + end + end + end end end @@ -187,4 +206,12 @@ def self.available_processor_count def self.cpu_quota processor_counter.cpu_quota end + + # The CPU shares requested by the process. For performance reasons the calculated + # value will be memoized on the first call. + # + # @return [Float, nil] CPU shares requested by the process, or nil if not set + def self.cpu_shares + processor_counter.cpu_shares + end end diff --git a/spec/concurrent/utility/processor_count_spec.rb b/spec/concurrent/utility/processor_count_spec.rb index fdc44b0ae..7a636640c 100644 --- a/spec/concurrent/utility/processor_count_spec.rb +++ b/spec/concurrent/utility/processor_count_spec.rb @@ -92,4 +92,26 @@ module Concurrent end end + + RSpec.describe '#cpu_shares' do + let(:counter) { Concurrent::Utility::ProcessorCounter.new } + + it 'returns a float when cgroups v2 sets a cpu.weight' do + expect(RbConfig::CONFIG).to receive(:[]).with("target_os").and_return("linux") + expect(File).to receive(:exist?).with("/sys/fs/cgroup/cpu.weight").and_return(true) + + expect(File).to receive(:read).with("/sys/fs/cgroup/cpu.weight").and_return("10000\n") + expect(counter.cpu_shares).to be == 256.0 + end + + it 'returns a float if cgroups v1 sets a cpu.shares' do + expect(RbConfig::CONFIG).to receive(:[]).with("target_os").and_return("linux") + expect(File).to receive(:exist?).with("/sys/fs/cgroup/cpu.weight").and_return(false) + expect(File).to receive(:exist?).with("/sys/fs/cgroup/cpu/cpu.shares").and_return(true) + + expect(File).to receive(:read).with("/sys/fs/cgroup/cpu/cpu.shares").and_return("512\n") + expect(counter.cpu_shares).to be == 0.5 + end + + end end