Created
July 20, 2020 09:00
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const std = @import("std"); | |
const Allocator = std.mem.Allocator; | |
const workload_size = 1 << 20; | |
const n_workloads = 4; | |
const repetition = 4; | |
const use_async = true; | |
const use_manual_prefetch = true; | |
const Cell = extern struct { | |
next_index: u64, | |
padding: [7]u64 = [_]u64{0} ** 7, | |
}; | |
fn initCells(allocator: *Allocator, size: usize) ![]Cell { | |
const order = try allocator.alloc(u64, size - 1); | |
defer allocator.free(order); | |
for (order) |*e, i| e.* = i + 1; | |
var rnd = std.rand.DefaultPrng.init(@bitCast(usize, std.time.milliTimestamp())); | |
rnd.random.shuffle(u64, order); | |
const cells = try allocator.alloc(Cell, size); | |
var prev: u64 = 0; | |
for (order) |i| { | |
cells[prev] = .{.next_index = i}; | |
prev = i; | |
} | |
cells[prev] = .{.next_index = size}; | |
return cells; | |
} | |
fn syncSum(workloads: *const [n_workloads][]const Cell) u64 { | |
var sum: u64 = 0; | |
for (workloads) |workload| { | |
var i: u64 = 0; | |
while (i != workload.len) { | |
i = workload[i].next_index; | |
sum += i; | |
} | |
} | |
return sum; | |
} | |
fn asyncWorker(workload: []const Cell, ready: *bool) u64 { | |
var partial_sum: u64 = 0; | |
var i: u64 = 0; | |
while (i != workload.len) { | |
if (use_manual_prefetch) { | |
asm volatile("prefetcht0 (%[addr])" :: [addr] "r" (&workload[i].next_index)); | |
suspend; | |
i = workload[i].next_index; | |
partial_sum += i; | |
} else { | |
i = workload[i].next_index; | |
suspend; | |
partial_sum += i; | |
} | |
} | |
ready.* = true; | |
return partial_sum; | |
} | |
fn asyncSum(workloads: *const [n_workloads][]const Cell) u64 { | |
var frames: [n_workloads]@Frame(asyncWorker) = undefined; | |
var ready = [_]bool{false} ** n_workloads; | |
for (frames) |*f, i| f.* = async asyncWorker(workloads[i], &ready[i]); | |
while (true) { | |
var any_unready = false; | |
for (frames) |*f, i| { | |
if (!ready[i]) { | |
resume f; | |
any_unready = true; | |
} | |
} | |
if (!any_unready) { | |
break; | |
} | |
} | |
var sum: u64 = 0; | |
for (frames) |*f| { | |
sum += nosuspend await f; | |
} | |
return sum; | |
} | |
pub fn main() !void { | |
const allocator = std.heap.page_allocator; | |
var workloads = [_][]Cell{&[_]Cell{}} ** n_workloads; | |
defer for (workloads) |w| allocator.free(w); | |
for (workloads) |*w| w.* = try initCells(allocator, workload_size); | |
var i: usize = 0; | |
while (i < repetition) : (i += 1) { | |
var timer = try std.time.Timer.start(); | |
const sum = if (use_async) asyncSum(&workloads) else syncSum(&workloads); | |
var dt = timer.read(); | |
std.debug.print("sum: {}, {} ms\n", .{sum, dt / 1_000_000}); | |
} | |
} |
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