diff --git a/src/Quantity.zig b/src/Quantity.zig index 815d756..1cfa4ba 100644 --- a/src/Quantity.zig +++ b/src/Quantity.zig @@ -527,3 +527,112 @@ test "Benchmark" { std.debug.print("\nAnti-optimisation sink: {d:.4}\n", .{gsink}); try std.testing.expect(gsink != 0); } + +test "Overhead Analysis: Quantity vs Native" { + const Io = std.Io; + const ITERS: usize = 100_000; + const SAMPLES: usize = 5; + const io = std.testing.io; + + const getTime = struct { + fn f(i: Io) Io.Timestamp { + return Io.Clock.awake.now(i); + } + }.f; + + const fold = struct { + fn f(comptime TT: type, s: *f64, v: TT) void { + s.* += if (comptime @typeInfo(TT) == .float) + @as(f64, @floatCast(v)) + else + @as(f64, @floatFromInt(v)); + } + }.f; + + // Helper to safely get a value of type T from a loop index + const getValT = struct { + fn f(comptime TT: type, i: usize) TT { + const v = (i % 100) + 1; + return if (comptime @typeInfo(TT) == .float) @floatFromInt(v) else @intCast(v); + } + }.f; + + const Types = .{ i32, i64, i128, f32, f64 }; + const TNames = .{ "i32", "i64", "i128", "f32", "f64" }; + const Ops = .{ "add", "mulBy", "divBy" }; + + var gsink: f64 = 0; + + std.debug.print( + \\ + \\ Quantity vs Native Overhead Analysis + \\ + \\┌───────────┬──────┬───────────┬───────────┬───────────┐ + \\│ Operation │ Type │ Native │ Quantity │ Slowdown │ + \\├───────────┼──────┼───────────┼───────────┼───────────┤ + \\ + , .{}); + + inline for (Ops) |op_name| { + inline for (Types, 0..) |T, tidx| { + var native_total_ns: f64 = 0; + var quantity_total_ns: f64 = 0; + + const M = Quantity(T, Dimensions.init(.{ .L = 1 }), Scales.init(.{})); + const S = Quantity(T, Dimensions.init(.{ .T = 1 }), Scales.init(.{})); + + for (0..SAMPLES) |_| { + // --- 1. Benchmark Native --- + var n_sink: T = 0; + const n_start = getTime(io); + for (0..ITERS) |i| { + const a = getValT(T, i); + const b = getValT(T, 2); + const r = if (comptime std.mem.eql(u8, op_name, "add")) + a + b + else if (comptime std.mem.eql(u8, op_name, "mulBy")) + a * b + else + if (comptime @typeInfo(T) == .int) @divTrunc(a, b) else a / b; + + if (comptime @typeInfo(T) == .float) n_sink += r else n_sink ^= r; + } + const n_end = getTime(io); + native_total_ns += @as(f64, @floatFromInt(n_start.durationTo(n_end).toNanoseconds())); + fold(T, &gsink, n_sink); + + // --- 2. Benchmark Quantity --- + var q_sink: T = 0; + const q_start = getTime(io); + for (0..ITERS) |i| { + const qa = M{ .value = getValT(T, i) }; + const qb = if (comptime std.mem.eql(u8, op_name, "divBy")) S{ .value = getValT(T, 2) } else M{ .value = getValT(T, 2) }; + + const r = if (comptime std.mem.eql(u8, op_name, "add")) + qa.add(qb) + else if (comptime std.mem.eql(u8, op_name, "mulBy")) + qa.mulBy(qb) + else + qa.divBy(qb); + + if (comptime @typeInfo(T) == .float) q_sink += r.value else q_sink ^= r.value; + } + const q_end = getTime(io); + quantity_total_ns += @as(f64, @floatFromInt(q_start.durationTo(q_end).toNanoseconds())); + fold(T, &gsink, q_sink); + } + + const avg_n = (native_total_ns / SAMPLES) / @as(f64, @floatFromInt(ITERS)); + const avg_q = (quantity_total_ns / SAMPLES) / @as(f64, @floatFromInt(ITERS)); + const slowdown = avg_q / avg_n; + + std.debug.print("│ {s:<9} │ {s:<4} │ {d:>7.2}ns │ {d:>7.2}ns │ {d:>8.2}x │\n", .{ + op_name, TNames[tidx], avg_n, avg_q, slowdown, + }); + } + std.debug.print("├───────────┼──────┼───────────┼───────────┼───────────┤\n", .{}); + } + + std.debug.print("└───────────┴──────┴───────────┴───────────┴───────────┘\n", .{}); + try std.testing.expect(gsink != 0); +}