Add mutex profiling to benchmark

cmd/tsdb/Makefile

@@ -1,5 +1,5 @@
 build:
-	@go1.8rc1 build .
+	@go build .
 	
 bench: build 
 	@echo ">> running benchmark"
@@ -8,3 +8,4 @@ bench: build
 	@go tool pprof --inuse_space -svg ./tsdb benchout/mem.prof > benchout/memprof.inuse.svg
 	@go tool pprof --alloc_space -svg ./tsdb benchout/mem.prof > benchout/memprof.alloc.svg
 	@go tool pprof -svg ./tsdb benchout/block.prof > benchout/blockprof.svg
+	@go tool pprof -svg ./tsdb benchout/mutex.prof > benchout/mutexprof.svg

cmd/tsdb/main.go

@@ -73,6 +73,7 @@ type writeBenchmark struct {
 	cpuprof   *os.File
 	memprof   *os.File
 	blockprof *os.File
+	mtxprof   *os.File
 }
 
 func NewBenchWriteCommand() *cobra.Command {
@@ -259,14 +260,20 @@ func (b *writeBenchmark) startProfiling() {
 	if err != nil {
 		exitWithError(fmt.Errorf("bench: could not create memory profile: %v", err))
 	}
-	runtime.MemProfileRate = 4096
+	runtime.MemProfileRate = 64 * 1024
 
 	// Start fatal profiling.
 	b.blockprof, err = os.Create(filepath.Join(b.outPath, "block.prof"))
 	if err != nil {
 		exitWithError(fmt.Errorf("bench: could not create block profile: %v", err))
 	}
-	runtime.SetBlockProfileRate(1)
+	runtime.SetBlockProfileRate(20)
+
+	b.mtxprof, err = os.Create(filepath.Join(b.outPath, "mutex.prof"))
+	if err != nil {
+		exitWithError(fmt.Errorf("bench: could not create mutex profile: %v", err))
+	}
+	runtime.SetMutexProfileFraction(20)
 }
 
 func (b *writeBenchmark) stopProfiling() {
@@ -286,6 +293,12 @@ func (b *writeBenchmark) stopProfiling() {
 		b.blockprof = nil
 		runtime.SetBlockProfileRate(0)
 	}
+	if b.mtxprof != nil {
+		pprof.Lookup("mutex").WriteTo(b.mtxprof, 0)
+		b.mtxprof.Close()
+		b.mtxprof = nil
+		runtime.SetMutexProfileFraction(0)
+	}
 }
 
 func measureTime(stage string, f func()) time.Duration {