[libc-commits] [libc] [libc] Add Minimum Time and Iterations, Reduce Epsilon (PR #100838)

[via libc-commits]

https://github.com/jameshu15869 created https://github.com/llvm/llvm-project/pull/100838

This PR adds minimums (50 iterations, 500 us, and epsilon of 0.0001) to ensure that all benchmarks run at least a set number of times before outputting a final measurement. 

>From 76cbe7ce92a3428fb402d766f9520847272e5a3a Mon Sep 17 00:00:00 2001
From: jameshu15869 <jhudson15869 at gmail.com>
Date: Fri, 26 Jul 2024 19:45:30 -0400
Subject: [PATCH] add minimum time, iterations and reduce epsilon

---
 libc/benchmarks/gpu/LibcGpuBenchmark.cpp | 1 +
 libc/benchmarks/gpu/LibcGpuBenchmark.h   | 5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/libc/benchmarks/gpu/LibcGpuBenchmark.cpp b/libc/benchmarks/gpu/LibcGpuBenchmark.cpp
index 031ad163c20da..a9a912538cd84 100644
--- a/libc/benchmarks/gpu/LibcGpuBenchmark.cpp
+++ b/libc/benchmarks/gpu/LibcGpuBenchmark.cpp
@@ -205,6 +205,7 @@ BenchmarkResult benchmark(const BenchmarkOptions &options,
     if (samples >= options.max_samples || iterations >= options.max_iterations)
       break;
     if (total_time >= options.min_duration && samples >= options.min_samples &&
+        total_iterations >= options.min_iterations &&
         change_ratio < options.epsilon)
       break;
 
diff --git a/libc/benchmarks/gpu/LibcGpuBenchmark.h b/libc/benchmarks/gpu/LibcGpuBenchmark.h
index f5cf4822f6fd3..ca5ad8a595d54 100644
--- a/libc/benchmarks/gpu/LibcGpuBenchmark.h
+++ b/libc/benchmarks/gpu/LibcGpuBenchmark.h
@@ -17,12 +17,13 @@ namespace benchmarks {
 
 struct BenchmarkOptions {
   uint32_t initial_iterations = 1;
+  uint32_t min_iterations = 50;
   uint32_t max_iterations = 10000000;
   uint32_t min_samples = 4;
   uint32_t max_samples = 1000;
-  int64_t min_duration = 0;                  // in nanoseconds (ns)
+  int64_t min_duration = 500 * 1000;         // 500 * 1000 nanoseconds = 500 us
   int64_t max_duration = 1000 * 1000 * 1000; // 1e9 nanoseconds = 1 second
-  double epsilon = 0.01;
+  double epsilon = 0.0001;
   double scaling_factor = 1.4;
 };