Add noisy_bench with some benchmarks that currently always time-out.

testing/device/CMakeLists.txt

@@ -0,0 +1,14 @@
+# Test that we're converging to an accurate mean + stdev without timing out:
+set(test_name nvbench.test.device.noisy_bench)
+add_executable(${test_name} noisy_bench.cu)
+target_link_libraries(${test_name} PRIVATE nvbench::main fmt)
+nvbench_config_target(${test_name})
+add_dependencies(nvbench.test.all ${test_name})
+
+if (NVBench_ENABLE_DEVICE_TESTING)
+  add_test(NAME ${test_name} COMMAND "$<TARGET_FILE:${test_name}>")
+  set_tests_properties(${test_name} PROPERTIES
+    # Any timeouts/warnings are hard failures for this test.
+    FAIL_REGULAR_EXPRESSION "Warn;timed out"
+  )
+endif()

testing/device/noisy_bench.cu

@@ -0,0 +1,146 @@
+/*
+ *  Copyright 2021 NVIDIA Corporation
+ *
+ *  Licensed under the Apache License, Version 2.0 with the LLVM exception
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.
+ *
+ *  You may obtain a copy of the License at
+ *
+ *      http://llvm.org/foundation/relicensing/LICENSE.txt
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#include <nvbench/nvbench.cuh>
+#include <nvbench/test_kernels.cuh>
+
+#include <fmt/format.h>
+
+#include <algorithm>
+#include <limits>
+#include <random>
+#include <stdexcept>
+
+void noisy_bench(nvbench::state &state)
+{
+  // time, convert ms -> s
+  const auto mean = static_cast<nvbench::float32_t>(state.get_float64("Mean")) /
+                    1000.f;
+  // rel stdev
+  const auto noise_pct =
+    static_cast<nvbench::float32_t>(state.get_float64("Noise"));
+  const auto noise = noise_pct / 100.f;
+  // abs stdev
+  const auto stdev = noise * mean;
+
+  std::minstd_rand rng{};
+  std::normal_distribution<nvbench::float32_t> dist(mean, stdev);
+
+  // cold tag will save time by disabling batch measurements
+  state.exec(nvbench::exec_tag::impl::cold, [&](nvbench::launch &launch) {
+    const auto seconds = dist(rng);
+    nvbench::sleep_kernel<<<1, 1, 0, launch.get_stream()>>>(seconds);
+  });
+
+  const auto measured_mean = static_cast<nvbench::float32_t>(
+    state.get_summary("Average GPU Time (Cold)").get_float64("value"));
+  const auto measured_noise = [&]() {
+    try
+    {
+      return static_cast<nvbench::float32_t>(
+        state.get_summary("GPU Relative Standard Deviation (Cold)")
+          .get_float64("value"));
+    }
+    catch (std::invalid_argument &)
+    {
+      return std::numeric_limits<nvbench::float32_t>::infinity();
+    }
+  }();
+  const auto measured_stdev = measured_noise * measured_mean;
+
+  const auto mean_error  = std::fabs(measured_mean - mean);
+  const auto stdev_error = std::fabs(measured_stdev - stdev);
+  const auto noise_error = std::fabs(measured_noise - noise);
+
+  const auto mean_threshold  = std::max(0.025f * mean, 8e-6f); // 2.5% or 8us
+  const auto stdev_threshold = std::max(0.05f * stdev, 5e-6f); // 5% or 5us
+
+  const auto mean_pass  = mean_error < mean_threshold;
+  const auto stdev_pass = stdev_error < stdev_threshold;
+
+  fmt::print("| {:^5} "
+             "| {:^12} | {:^12} "
+             "| {:^12} | {:^12} | {:^4} |\n",
+             "",
+             "Expected",
+             "Measured",
+             "Error",
+             "Threshold",
+             "Flag");
+  fmt::print("|{:-^7}"
+             "|{:-^14}|{:-^14}"
+             "|{:-^14}|{:-^14}|{:-^6}|\n",
+             "",
+             "",
+             "",
+             "",
+             "",
+             "");
+  fmt::print("| Mean  "
+             "| {:>9.6f} ms | {:>9.6f} ms "
+             "| {:>9.6f} ms | {:>9.6f} ms | {:4} |\n"
+             "| Stdev "
+             "| {:>9.6f} ms | {:>9.6f} ms "
+             "| {:>9.6f} ms | {:>9.6f} ms | {:4} |\n"
+             "| Noise "
+             "| {:>9.6f}%   | {:>9.6f}%   "
+             "| {:>9.6f}%   | {:5}        | {:4} |\n",
+             mean * 1000,
+             measured_mean * 1000,
+             mean_error * 1000,
+             mean_threshold * 1000,
+             mean_pass ? "" : "!!!!",
+
+             stdev * 1000,
+             measured_stdev * 1000,
+             stdev_error * 1000,
+             stdev_threshold * 1000,
+             stdev_pass ? "" : "!!!!",
+
+             noise * 100,
+             measured_noise * 100,
+             noise_error * 100,
+             "",
+             "");
+
+  if (!mean_pass)
+  {
+    // This isn't actually logged, it just tells ctest to mark the test as
+    // skipped as a soft-failure.
+    fmt::print("Warn: Mean error exceeds threshold: ({:.3} ms > {:.3} ms)\n",
+               mean_error * 1000,
+               mean_threshold * 1000);
+  }
+
+  if (!stdev_pass)
+  {
+    // This isn't actually logged, it just tells ctest to mark the test as
+    // skipped as a soft-failure.
+    fmt::print("Warn: Stdev error exceeds threshold: "
+               "({:.6} ms > {:.6} ms, noise: {:.3}%)\n",
+               stdev_error * 1000,
+               stdev_threshold * 1000,
+               measured_noise * 100);
+  }
+}
+NVBENCH_BENCH(noisy_bench)
+  .add_float64_axis("Mean", {0.05, 0.1, 0.5, 1.0, 10.0}) // ms
+  .add_float64_axis("Noise", {0.1, 5., 25.})             // %
+  // disable this; we want to test that the benchmarking loop will still exit
+  // when max_noise is never reached:
+  .set_max_noise(0.0000001);