Add turbocharged twin scenario and cross-platform test harness

tools/thread_benchmark.cpp

@@ -0,0 +1,54 @@
+#include "FluidSim/Fluid.hpp"
+#include <barrier>
+#include <chrono>
+#include <iostream>
+#include <thread>
+using namespace fluidsim::port;
+int main() {
+    for (auto size : {std::pair{6, 10}, std::pair{64, 256}}) {
+        const int steps = 1000;
+        for (int workers : {1, 2, 4}) {
+            std::vector<Pipe1D> p;
+            for (int i = 0; i < size.first; i++)
+                p.emplace_back(.001f, 2, size.second);
+            auto advance = [&](int worker) {
+                for (int k = worker; k < size.first; k += workers) {
+                    auto &a = p[k];
+                    auto l = a.state(0), r = a.state(size.second - 1);
+                    l.velocity = -l.velocity;
+                    r.velocity = -r.velocity;
+                    a.left_ghost = l;
+                    a.right_ghost = r;
+                    a.advance(.0000005f);
+                }
+            };
+            std::barrier sync(workers + 1);
+            std::vector<std::jthread> pool;
+            if (workers > 1)
+                for (int k = 0; k < workers; k++)
+                    pool.emplace_back([&, k] {
+                        for (int i = 0; i < steps; i++) {
+                            sync.arrive_and_wait();
+                            advance(k);
+                            sync.arrive_and_wait();
+                        }
+                    });
+            auto start = std::chrono::steady_clock::now();
+            for (int i = 0; i < steps; i++) {
+                if (workers == 1)
+                    advance(0);
+                else {
+                    sync.arrive_and_wait();
+                    sync.arrive_and_wait();
+                }
+            }
+            double sec = std::chrono::duration<double>(std::chrono::steady_clock::now() - start).count();
+            pool.clear();
+            double sum = 0;
+            for (auto &q : p)
+                sum += q.state(0).pressure;
+            std::cout << "pipes=" << size.first << " cells/pipe=" << size.second << " workers=" << workers
+                      << " steps=" << steps << " seconds=" << sec << " checksum=" << sum << '\n';
+        }
+    }
+}