From 7544eeb242d0aba2da054a1663e043feaedb9618 Mon Sep 17 00:00:00 2001
From: Zach Koopmans <zkoopmans@google.com>
Date: Fri, 19 Feb 2021 17:10:27 -0800
Subject: Correctly set and respect b.N in fio benchmark.

fio should scale by written/read bytes and not iterate runs
of the fio container.

PiperOrigin-RevId: 358511771
---
 test/benchmarks/fs/fio_test.go | 34 ++++++++++++----------------------
 test/benchmarks/tools/fio.go   | 11 ++++-------
 2 files changed, 16 insertions(+), 29 deletions(-)

diff --git a/test/benchmarks/fs/fio_test.go b/test/benchmarks/fs/fio_test.go
index 242374e2c..cc2d1cbbc 100644
--- a/test/benchmarks/fs/fio_test.go
+++ b/test/benchmarks/fs/fio_test.go
@@ -34,37 +34,31 @@ func BenchmarkFio(b *testing.B) {
 	testCases := []tools.Fio{
 		{
 			Test:      "write",
-			Size:      b.N,
 			BlockSize: 4,
 			IODepth:   4,
 		},
 		{
 			Test:      "write",
-			Size:      b.N,
 			BlockSize: 1024,
 			IODepth:   4,
 		},
 		{
 			Test:      "read",
-			Size:      b.N,
 			BlockSize: 4,
 			IODepth:   4,
 		},
 		{
 			Test:      "read",
-			Size:      b.N,
 			BlockSize: 1024,
 			IODepth:   4,
 		},
 		{
 			Test:      "randwrite",
-			Size:      b.N,
 			BlockSize: 4,
 			IODepth:   4,
 		},
 		{
 			Test:      "randread",
-			Size:      b.N,
 			BlockSize: 4,
 			IODepth:   4,
 		},
@@ -95,6 +89,8 @@ func BenchmarkFio(b *testing.B) {
 				b.Fatalf("Failed to parser paramters: %v", err)
 			}
 			b.Run(name, func(b *testing.B) {
+				b.StopTimer()
+				tc.Size = b.N
 				ctx := context.Background()
 				container := machine.GetContainer(ctx, b)
 				defer container.CleanUp(ctx)
@@ -141,24 +137,18 @@ func BenchmarkFio(b *testing.B) {
 				}
 				cmd := tc.MakeCmd(outfile)
 
-				b.ResetTimer()
-				b.StopTimer()
-
-				for i := 0; i < b.N; i++ {
-					if err := harness.DropCaches(machine); err != nil {
-						b.Fatalf("failed to drop caches: %v", err)
-					}
+				if err := harness.DropCaches(machine); err != nil {
+					b.Fatalf("failed to drop caches: %v", err)
+				}
 
-					// Run fio.
-					b.StartTimer()
-					data, err := container.Exec(ctx, dockerutil.ExecOpts{}, cmd...)
-					if err != nil {
-						b.Fatalf("failed to run cmd %v: %v", cmd, err)
-					}
-					b.StopTimer()
-					b.SetBytes(1024 * 1024) // Bytes for go reporting (Size is in megabytes).
-					tc.Report(b, data)
+				// Run fio.
+				b.StartTimer()
+				data, err := container.Exec(ctx, dockerutil.ExecOpts{}, cmd...)
+				if err != nil {
+					b.Fatalf("failed to run cmd %v: %v", cmd, err)
 				}
+				b.StopTimer()
+				tc.Report(b, data)
 			})
 		}
 	}
diff --git a/test/benchmarks/tools/fio.go b/test/benchmarks/tools/fio.go
index f6324c3ab..ea12436d2 100644
--- a/test/benchmarks/tools/fio.go
+++ b/test/benchmarks/tools/fio.go
@@ -62,18 +62,15 @@ func (f *Fio) Report(b *testing.B, output string) {
 
 // parseBandwidth reports the bandwidth in b/s.
 func (f *Fio) parseBandwidth(data string, isRead bool) (float64, error) {
+	op := "write"
 	if isRead {
-		result, err := f.parseFioJSON(data, "read", "bw")
-		if err != nil {
-			return 0, err
-		}
-		return 1024 * result, nil
+		op = "read"
 	}
-	result, err := f.parseFioJSON(data, "write", "bw")
+	result, err := f.parseFioJSON(data, op, "bw")
 	if err != nil {
 		return 0, err
 	}
-	return 1024 * result, nil
+	return result * 1024, nil
 }
 
 // parseIOps reports the write IO per second metric.
-- 
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