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Show Major/minor stats on per-iteration gc benchmarks #489

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09a1d20
Show Major/minor stats on per-iteration gc benchmarks
eightbitraptor Mar 12, 2026
3f978f6
Show heap breakdown in gc benches
eightbitraptor Mar 16, 2026
fad7781
Add total heap memory to heap summary stats
eightbitraptor Mar 16, 2026
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47 changes: 47 additions & 0 deletions harness-gc/harness.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,8 @@ def run_benchmark(_num_itrs_hint, **, &block)
marking_times = []
sweeping_times = []
gc_counts = []
major_counts = []
minor_counts = []
gc_heap_deltas = []
total_time = 0
num_itrs = 0
Expand All @@ -47,6 +49,9 @@ def run_benchmark(_num_itrs_hint, **, &block)
header << " marking" if has_marking
header << " sweeping" if has_sweeping
header << " gc_count"
header << " major"
header << " minor"
header << " maj/min"
puts header

begin
Expand All @@ -63,17 +68,25 @@ def run_benchmark(_num_itrs_hint, **, &block)
mark_delta = has_marking ? gc_after[:marking_time] - gc_before[:marking_time] : 0
sweep_delta = has_sweeping ? gc_after[:sweeping_time] - gc_before[:sweeping_time] : 0
count_delta = gc_after[:count] - gc_before[:count]
major_delta = gc_after[:major_gc_count] - gc_before[:major_gc_count]
minor_delta = gc_after[:minor_gc_count] - gc_before[:minor_gc_count]
ratio_str = minor_delta > 0 ? "%.2f" % (major_delta.to_f / minor_delta) : "-"

itr_str = "%4s %6s" % ["##{num_itrs}:", "#{time_ms}ms"]
itr_str << " %9.1fms" % mark_delta if has_marking
itr_str << " %9.1fms" % sweep_delta if has_sweeping
itr_str << " %9d" % count_delta
itr_str << " %9d" % major_delta
itr_str << " %9d" % minor_delta
itr_str << " %9s" % ratio_str
puts itr_str

times << time
marking_times << mark_delta
sweeping_times << sweep_delta
gc_counts << count_delta
major_counts << major_delta
minor_counts << minor_delta
gc_heap_deltas << gc_stat_heap_delta(heap_before, heap_after)
total_time += time
end until num_itrs >= WARMUP_ITRS + MIN_BENCH_ITRS and total_time >= MIN_BENCH_TIME
Expand All @@ -88,8 +101,19 @@ def run_benchmark(_num_itrs_hint, **, &block)
extra["gc_sweeping_time_bench"] = sweeping_times[bench_range]
extra["gc_count_warmup"] = gc_counts[warmup_range]
extra["gc_count_bench"] = gc_counts[bench_range]
extra["gc_major_count_warmup"] = major_counts[warmup_range]
extra["gc_major_count_bench"] = major_counts[bench_range]
extra["gc_minor_count_warmup"] = minor_counts[warmup_range]
extra["gc_minor_count_bench"] = minor_counts[bench_range]
extra["gc_stat_heap_deltas"] = gc_heap_deltas[bench_range]

# Snapshot heap utilisation after benchmark
if GC.respond_to?(:stat_heap)
GC.start(full_mark: true)
heap_snapshot = GC.stat_heap
extra["gc_heap_final"] = heap_snapshot.transform_values { |v| v.is_a?(Hash) ? v.dup : v }
end

return_results(times[warmup_range], times[bench_range], **extra)

non_warmups = times[bench_range]
Expand All @@ -109,4 +133,27 @@ def run_benchmark(_num_itrs_hint, **, &block)
puts "Average sweeping time: %.1fms" % avg_sweep
end
end

# Print heap utilisation table
if heap_snapshot
page_size = defined?(GC::INTERNAL_CONSTANTS) ? GC::INTERNAL_CONSTANTS[:HEAP_PAGE_SIZE] : nil

puts "\nHeap utilisation (after full GC):"
header = "heap slot_size eden_slots live_slots free_slots eden_pages live_pct mem_KiB"
puts header

heap_snapshot.each do |idx, stats|
slot_size = stats[:slot_size] || 0
eden_slots = stats[:heap_eden_slots] || 0
live_slots = stats[:heap_live_slots] || 0
free_slots = stats[:heap_free_slots] || 0
eden_pages = stats[:heap_eden_pages] || 0
live_pct = eden_slots > 0 ? (live_slots * 100.0 / eden_slots) : 0.0
mem_kib = page_size ? (eden_pages * page_size / 1024.0) : 0.0

puts "%4d %9d %10d %10d %10d %11d %7.1f%% %7.1f" % [
idx, slot_size, eden_slots, live_slots, free_slots, eden_pages, live_pct, mem_kib
]
end
end
end
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