Report RSS and the commit charge on Windows

harness/harness-common.rb

@@ -73,6 +73,8 @@ def get_rss
     # First, grab a line like "62796 kB". Checking the Linux kernel source, Rss will always be in kB.
     rss_desc = File.read(mem_rollup_file).lines.detect { |line| line.start_with?("Rss") }.split(":", 2)[1][/(\d+)/, 1]
     1024 * Integer(rss_desc)
+  elsif is_windows
+    get_windows_memory_counters&.fetch(:working_set) || 0
   else
     # Collect our own peak mem usage as soon as reasonable after finishing the last iteration.
     # This method is only accurate to kilobytes, but is nicely portable and doesn't require
@@ -176,6 +178,46 @@ def self.function(name, args, ret)
   end
 end
 
+# Memoized like ProcPidRusage, since load_fiddle alone takes about 0.1 ms on Windows.
+module WindowsMemoryCounters
+  @resolved = false
+
+  def self.fn
+    return @fn if @resolved
+
+    @resolved = true
+    @fn = begin
+      load_fiddle
+      process = WindowsKernel32.function('GetCurrentProcess', [], Fiddle::TYPE_VOIDP).call
+      get_info = WindowsKernel32.function('K32GetProcessMemoryInfo', [Fiddle::TYPE_VOIDP, Fiddle::TYPE_VOIDP, Fiddle::TYPE_INT], Fiddle::TYPE_INT)
+      ->(buffer) { get_info.call(process, buffer, buffer.bytesize) }
+    rescue LoadError, Fiddle::DLError, NameError
+      warn "Failed to get memory counters: #{$!.message}"
+      nil
+    end
+  end
+end
+
+# Returns memory counters of this process in bytes. The working set is the Windows counterpart of RSS,
+# and the commit charge (PagefileUsage) is the private memory the process has committed.
+def get_windows_memory_counters
+  get_info = WindowsMemoryCounters.fn
+  return nil unless get_info
+
+  # PROCESS_MEMORY_COUNTERS: two DWORDs followed by eight SIZE_Ts.
+  buffer = "\0".b * (8 + 8 * Fiddle::SIZEOF_SIZE_T)
+  buffer[0, 4] = [buffer.bytesize].pack('L')
+  return nil if get_info.call(buffer).zero?
+
+  peak_working_set, working_set, _, _, _, _, commit_charge, peak_commit_charge = buffer.unpack('x8J8')
+  {
+    working_set: working_set,
+    peak_working_set: peak_working_set,
+    commit_charge: commit_charge,
+    peak_commit_charge: peak_commit_charge,
+  }
+end
+
 def pin_to_cpu(cpu)
   load_fiddle
   # Etc.nprocessors counts the CPUs of every processor group, but the mask holds those of one group only.
@@ -210,6 +252,8 @@ def raise_priority
 end
 
 def get_maxrss
+  return get_windows_memory_counters&.fetch(:peak_working_set) if is_windows
+
   load_fiddle
 
   require 'rbconfig/sizeof'
@@ -267,6 +311,10 @@ def return_results(warmup_iterations, bench_iterations, **extra)
   if maxrss = get_maxrss
     ruby_bench_results["maxrss"] = maxrss
   end
+  if is_windows && (counters = get_windows_memory_counters)
+    ruby_bench_results["commit_charge"] = counters[:commit_charge]
+    ruby_bench_results["peak_commit_charge"] = counters[:peak_commit_charge]
+  end
 
   # If YJIT or ZJIT is enabled, show some of its stats unless it does by itself.
   if yjit_stats