tweak more things to get it all to work

.evergreen/config.yml

@@ -385,10 +385,10 @@ functions:
         working_dir: "src"
         script: |
           ${PREPARE_SHELL}
-          TEST_CMD="bundle exec rake driver_bench" .evergreen/run-tests.sh
+          TEST_CMD="bundle exec rake driver_bench" PERFORMANCE_RESULTS_FILE="$PROJECT_DIRECTORY/perf.json" .evergreen/run-tests.sh
     - command: perf.send
       params:
-        file: ./results.json
+        file: "${PROJECT_DIRECTORY}/perf.json"
 
   "run tests":
     - command: shell.exec

.evergreen/config/common.yml.erb

@@ -382,10 +382,10 @@ functions:
         working_dir: "src"
         script: |
           ${PREPARE_SHELL}
-          TEST_CMD="bundle exec rake driver_bench" .evergreen/run-tests.sh
+          TEST_CMD="bundle exec rake driver_bench" PERFORMANCE_RESULTS_FILE="$PROJECT_DIRECTORY/perf.json" .evergreen/run-tests.sh
     - command: perf.send
       params:
-        file: ./results.json
+        file: "${PROJECT_DIRECTORY}/perf.json"
 
   "run tests":
     - command: shell.exec

profile/driver_bench/base.rb

@@ -85,7 +85,7 @@ def run_benchmark
 
           loop do
             before_task
-            timing = without_gc { Benchmark.realtime { debug_mode? ? sleep(0.1) : do_task } }
+            timing = consider_gc { Benchmark.realtime { debug_mode? ? sleep(0.1) : do_task } }
             after_task
 
             iteration_count += 1
@@ -111,12 +111,18 @@ def new_client(uri = ENV['MONGODB_URI'])
         Mongo::Client.new(uri)
       end
 
-      # Runs a given block with GC disabled.
-      def without_gc
-        GC.disable
+      # Takes care of garbage collection considerations before
+      # running the block.
+      #
+      # Set BENCHMARK_NO_GC environment variable to suppress GC during
+      # the core benchmark tasks; note that this may result in obscure issues
+      # due to memory pressures on larger benchmarks.
+      def consider_gc
+        GC.start
+        GC.disable if ENV['BENCHMARK_NO_GC']
         yield
       ensure
-        GC.enable
+        GC.enable if ENV['BENCHMARK_NO_GC']
       end
 
       # By default, the file name is assumed to be relative to the

profile/driver_bench/multi_doc/find_many.rb

@@ -21,8 +21,11 @@ def file_name
         def setup
           super
 
-          docs = Array.new(10_000) { dataset.first }
-          @collection.insert_many(docs)
+          prototype = dataset.first
+          10.times do
+            docs = Array.new(1000, prototype)
+            @collection.insert_many(docs)
+          end
         end
 
         def do_task

profile/driver_bench/single_doc/find_one_by_id.rb

@@ -19,8 +19,10 @@ def file_name
         def setup
           super
 
-          docs = Array.new(10_000) { |i| dataset.merge(_id: i + 1) }
-          @collection.insert_many(docs)
+          10.times do |i|
+            docs = Array.new(1000) { |j| dataset.merge(_id: (i * 1000) + j + 1) }
+            @collection.insert_many(docs)
+          end
         end
 
         def do_task

profile/driver_bench/suite.rb

@@ -73,16 +73,21 @@ def run_benchmark(klass)
       end
 
       def compile_perf_data(result)
-        percentile_data = PERCENTILES.each_with_object({}) do |n, hash|
-          hash["time-#{n}%"] = result[:percentiles][n]
+        percentile_data = PERCENTILES.map do |percentile|
+          { 'name' => "time-#{percentile}%",
+            'value' => result[:percentiles][percentile] }
         end
 
         {
           'info' => {
             'test_name' => result[:name],
             'args' => {},
           },
-          'metrics' => percentile_data.merge('score' => result[:score]),
+          'metrics' => [
+            { 'name' => 'score',
+              'value' => result[:score] },
+            *percentile_data
+          ]
         }
       end
 
@@ -105,27 +110,32 @@ def compile_benchmarks(benches)
               'test_name' => bench,
               'args' => {}
             },
-            'metrics' => {
-              'score' => score
-            }
+            'metrics' => [
+              { 'name' => 'score',
+                'value' => score }
+            ]
           }
         end
       end
 
+      # rubocop:disable Metrics/AbcSize
       def summarize_perf_data(data)
         puts '===== Performance Results ====='
         data.each do |item|
-          puts format('%s : %4.4g', item['info']['test_name'], item['metrics']['score'])
-          next unless item['metrics']['time-10%']
+          puts format('%s : %4.4g', item['info']['test_name'], item['metrics'][0]['value'])
+          next unless item['metrics'].length > 1
 
-          PERCENTILES.each do |n|
-            puts format('  %d%% : %4.4g', n, item['metrics']["time-#{n}%"])
+          item['metrics'].each do |metric|
+            next if metric['name'] == 'score'
+
+            puts format('  %s : %4.4g', metric['name'], metric['value'])
           end
         end
       end
+      # rubocop:enable Metrics/AbcSize
 
-      def save_perf_data(data)
-        File.write('results.json', data.to_json)
+      def save_perf_data(data, file_name: ENV['PERFORMANCE_RESULTS_FILE'] || 'results.json')
+        File.write(file_name, data.to_json)
       end
     end
   end