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-rw-r--r--src/runtime/trace/trace_test.go817
1 files changed, 817 insertions, 0 deletions
diff --git a/src/runtime/trace/trace_test.go b/src/runtime/trace/trace_test.go
new file mode 100644
index 0000000..23a8d11
--- /dev/null
+++ b/src/runtime/trace/trace_test.go
@@ -0,0 +1,817 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package trace_test
+
+import (
+ "bytes"
+ "context"
+ "flag"
+ "fmt"
+ "internal/goexperiment"
+ "internal/profile"
+ "internal/race"
+ "internal/trace"
+ "io"
+ "net"
+ "os"
+ "runtime"
+ "runtime/pprof"
+ . "runtime/trace"
+ "strconv"
+ "strings"
+ "sync"
+ "testing"
+ "time"
+)
+
+var (
+ saveTraces = flag.Bool("savetraces", false, "save traces collected by tests")
+)
+
+// TestEventBatch tests Flush calls that happen during Start
+// don't produce corrupted traces.
+func TestEventBatch(t *testing.T) {
+ if race.Enabled {
+ t.Skip("skipping in race mode")
+ }
+ if IsEnabled() {
+ t.Skip("skipping because -test.trace is set")
+ }
+ if testing.Short() {
+ t.Skip("skipping in short mode")
+ }
+ if goexperiment.ExecTracer2 {
+ t.Skip("skipping because this test is incompatible with the new tracer")
+ }
+ // During Start, bunch of records are written to reflect the current
+ // snapshot of the program, including state of each goroutines.
+ // And some string constants are written to the trace to aid trace
+ // parsing. This test checks Flush of the buffer occurred during
+ // this process doesn't cause corrupted traces.
+ // When a Flush is called during Start is complicated
+ // so we test with a range of number of goroutines hoping that one
+ // of them triggers Flush.
+ // This range was chosen to fill up a ~64KB buffer with traceEvGoCreate
+ // and traceEvGoWaiting events (12~13bytes per goroutine).
+ for g := 4950; g < 5050; g++ {
+ n := g
+ t.Run("G="+strconv.Itoa(n), func(t *testing.T) {
+ var wg sync.WaitGroup
+ wg.Add(n)
+
+ in := make(chan bool, 1000)
+ for i := 0; i < n; i++ {
+ go func() {
+ <-in
+ wg.Done()
+ }()
+ }
+ buf := new(bytes.Buffer)
+ if err := Start(buf); err != nil {
+ t.Fatalf("failed to start tracing: %v", err)
+ }
+
+ for i := 0; i < n; i++ {
+ in <- true
+ }
+ wg.Wait()
+ Stop()
+
+ _, err := trace.Parse(buf, "")
+ if err == trace.ErrTimeOrder {
+ t.Skipf("skipping trace: %v", err)
+ }
+
+ if err != nil {
+ t.Fatalf("failed to parse trace: %v", err)
+ }
+ })
+ }
+}
+
+func TestTraceStartStop(t *testing.T) {
+ if IsEnabled() {
+ t.Skip("skipping because -test.trace is set")
+ }
+ buf := new(bytes.Buffer)
+ if err := Start(buf); err != nil {
+ t.Fatalf("failed to start tracing: %v", err)
+ }
+ Stop()
+ size := buf.Len()
+ if size == 0 {
+ t.Fatalf("trace is empty")
+ }
+ time.Sleep(100 * time.Millisecond)
+ if size != buf.Len() {
+ t.Fatalf("trace writes after stop: %v -> %v", size, buf.Len())
+ }
+ saveTrace(t, buf, "TestTraceStartStop")
+}
+
+func TestTraceDoubleStart(t *testing.T) {
+ if IsEnabled() {
+ t.Skip("skipping because -test.trace is set")
+ }
+ Stop()
+ buf := new(bytes.Buffer)
+ if err := Start(buf); err != nil {
+ t.Fatalf("failed to start tracing: %v", err)
+ }
+ if err := Start(buf); err == nil {
+ t.Fatalf("succeed to start tracing second time")
+ }
+ Stop()
+ Stop()
+}
+
+func TestTrace(t *testing.T) {
+ if IsEnabled() {
+ t.Skip("skipping because -test.trace is set")
+ }
+ if goexperiment.ExecTracer2 {
+ // An equivalent test exists in internal/trace/v2.
+ t.Skip("skipping because this test is incompatible with the new tracer")
+ }
+ buf := new(bytes.Buffer)
+ if err := Start(buf); err != nil {
+ t.Fatalf("failed to start tracing: %v", err)
+ }
+ Stop()
+ saveTrace(t, buf, "TestTrace")
+ _, err := trace.Parse(buf, "")
+ if err == trace.ErrTimeOrder {
+ t.Skipf("skipping trace: %v", err)
+ }
+ if err != nil {
+ t.Fatalf("failed to parse trace: %v", err)
+ }
+}
+
+func parseTrace(t *testing.T, r io.Reader) ([]*trace.Event, map[uint64]*trace.GDesc) {
+ res, err := trace.Parse(r, "")
+ if err == trace.ErrTimeOrder {
+ t.Skipf("skipping trace: %v", err)
+ }
+ if err != nil {
+ t.Fatalf("failed to parse trace: %v", err)
+ }
+ gs := trace.GoroutineStats(res.Events)
+ for goid := range gs {
+ // We don't do any particular checks on the result at the moment.
+ // But still check that RelatedGoroutines does not crash, hang, etc.
+ _ = trace.RelatedGoroutines(res.Events, goid)
+ }
+ return res.Events, gs
+}
+
+func testBrokenTimestamps(t *testing.T, data []byte) {
+ // On some processors cputicks (used to generate trace timestamps)
+ // produce non-monotonic timestamps. It is important that the parser
+ // distinguishes logically inconsistent traces (e.g. missing, excessive
+ // or misordered events) from broken timestamps. The former is a bug
+ // in tracer, the latter is a machine issue.
+ // So now that we have a consistent trace, test that (1) parser does
+ // not return a logical error in case of broken timestamps
+ // and (2) broken timestamps are eventually detected and reported.
+ trace.BreakTimestampsForTesting = true
+ defer func() {
+ trace.BreakTimestampsForTesting = false
+ }()
+ for i := 0; i < 1e4; i++ {
+ _, err := trace.Parse(bytes.NewReader(data), "")
+ if err == trace.ErrTimeOrder {
+ return
+ }
+ if err != nil {
+ t.Fatalf("failed to parse trace: %v", err)
+ }
+ }
+}
+
+func TestTraceStress(t *testing.T) {
+ switch runtime.GOOS {
+ case "js", "wasip1":
+ t.Skip("no os.Pipe on " + runtime.GOOS)
+ }
+ if IsEnabled() {
+ t.Skip("skipping because -test.trace is set")
+ }
+ if testing.Short() {
+ t.Skip("skipping in -short mode")
+ }
+ if goexperiment.ExecTracer2 {
+ // An equivalent test exists in internal/trace/v2.
+ t.Skip("skipping because this test is incompatible with the new tracer")
+ }
+
+ var wg sync.WaitGroup
+ done := make(chan bool)
+
+ // Create a goroutine blocked before tracing.
+ wg.Add(1)
+ go func() {
+ <-done
+ wg.Done()
+ }()
+
+ // Create a goroutine blocked in syscall before tracing.
+ rp, wp, err := os.Pipe()
+ if err != nil {
+ t.Fatalf("failed to create pipe: %v", err)
+ }
+ defer func() {
+ rp.Close()
+ wp.Close()
+ }()
+ wg.Add(1)
+ go func() {
+ var tmp [1]byte
+ rp.Read(tmp[:])
+ <-done
+ wg.Done()
+ }()
+ time.Sleep(time.Millisecond) // give the goroutine above time to block
+
+ buf := new(bytes.Buffer)
+ if err := Start(buf); err != nil {
+ t.Fatalf("failed to start tracing: %v", err)
+ }
+
+ procs := runtime.GOMAXPROCS(10)
+ time.Sleep(50 * time.Millisecond) // test proc stop/start events
+
+ go func() {
+ runtime.LockOSThread()
+ for {
+ select {
+ case <-done:
+ return
+ default:
+ runtime.Gosched()
+ }
+ }
+ }()
+
+ runtime.GC()
+ // Trigger GC from malloc.
+ n := int(1e3)
+ if isMemoryConstrained() {
+ // Reduce allocation to avoid running out of
+ // memory on the builder - see issue/12032.
+ n = 512
+ }
+ for i := 0; i < n; i++ {
+ _ = make([]byte, 1<<20)
+ }
+
+ // Create a bunch of busy goroutines to load all Ps.
+ for p := 0; p < 10; p++ {
+ wg.Add(1)
+ go func() {
+ // Do something useful.
+ tmp := make([]byte, 1<<16)
+ for i := range tmp {
+ tmp[i]++
+ }
+ _ = tmp
+ <-done
+ wg.Done()
+ }()
+ }
+
+ // Block in syscall.
+ wg.Add(1)
+ go func() {
+ var tmp [1]byte
+ rp.Read(tmp[:])
+ <-done
+ wg.Done()
+ }()
+
+ // Test timers.
+ timerDone := make(chan bool)
+ go func() {
+ time.Sleep(time.Millisecond)
+ timerDone <- true
+ }()
+ <-timerDone
+
+ // A bit of network.
+ ln, err := net.Listen("tcp", "127.0.0.1:0")
+ if err != nil {
+ t.Fatalf("listen failed: %v", err)
+ }
+ defer ln.Close()
+ go func() {
+ c, err := ln.Accept()
+ if err != nil {
+ return
+ }
+ time.Sleep(time.Millisecond)
+ var buf [1]byte
+ c.Write(buf[:])
+ c.Close()
+ }()
+ c, err := net.Dial("tcp", ln.Addr().String())
+ if err != nil {
+ t.Fatalf("dial failed: %v", err)
+ }
+ var tmp [1]byte
+ c.Read(tmp[:])
+ c.Close()
+
+ go func() {
+ runtime.Gosched()
+ select {}
+ }()
+
+ // Unblock helper goroutines and wait them to finish.
+ wp.Write(tmp[:])
+ wp.Write(tmp[:])
+ close(done)
+ wg.Wait()
+
+ runtime.GOMAXPROCS(procs)
+
+ Stop()
+ saveTrace(t, buf, "TestTraceStress")
+ trace := buf.Bytes()
+ parseTrace(t, buf)
+ testBrokenTimestamps(t, trace)
+}
+
+// isMemoryConstrained reports whether the current machine is likely
+// to be memory constrained.
+// This was originally for the openbsd/arm builder (Issue 12032).
+// TODO: move this to testenv? Make this look at memory? Look at GO_BUILDER_NAME?
+func isMemoryConstrained() bool {
+ if runtime.GOOS == "plan9" {
+ return true
+ }
+ switch runtime.GOARCH {
+ case "arm", "mips", "mipsle":
+ return true
+ }
+ return false
+}
+
+// Do a bunch of various stuff (timers, GC, network, etc) in a separate goroutine.
+// And concurrently with all that start/stop trace 3 times.
+func TestTraceStressStartStop(t *testing.T) {
+ switch runtime.GOOS {
+ case "js", "wasip1":
+ t.Skip("no os.Pipe on " + runtime.GOOS)
+ }
+ if IsEnabled() {
+ t.Skip("skipping because -test.trace is set")
+ }
+ if goexperiment.ExecTracer2 {
+ // An equivalent test exists in internal/trace/v2.
+ t.Skip("skipping because this test is incompatible with the new tracer")
+ }
+ defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(8))
+ outerDone := make(chan bool)
+
+ go func() {
+ defer func() {
+ outerDone <- true
+ }()
+
+ var wg sync.WaitGroup
+ done := make(chan bool)
+
+ wg.Add(1)
+ go func() {
+ <-done
+ wg.Done()
+ }()
+
+ rp, wp, err := os.Pipe()
+ if err != nil {
+ t.Errorf("failed to create pipe: %v", err)
+ return
+ }
+ defer func() {
+ rp.Close()
+ wp.Close()
+ }()
+ wg.Add(1)
+ go func() {
+ var tmp [1]byte
+ rp.Read(tmp[:])
+ <-done
+ wg.Done()
+ }()
+ time.Sleep(time.Millisecond)
+
+ go func() {
+ runtime.LockOSThread()
+ for {
+ select {
+ case <-done:
+ return
+ default:
+ runtime.Gosched()
+ }
+ }
+ }()
+
+ runtime.GC()
+ // Trigger GC from malloc.
+ n := int(1e3)
+ if isMemoryConstrained() {
+ // Reduce allocation to avoid running out of
+ // memory on the builder.
+ n = 512
+ }
+ for i := 0; i < n; i++ {
+ _ = make([]byte, 1<<20)
+ }
+
+ // Create a bunch of busy goroutines to load all Ps.
+ for p := 0; p < 10; p++ {
+ wg.Add(1)
+ go func() {
+ // Do something useful.
+ tmp := make([]byte, 1<<16)
+ for i := range tmp {
+ tmp[i]++
+ }
+ _ = tmp
+ <-done
+ wg.Done()
+ }()
+ }
+
+ // Block in syscall.
+ wg.Add(1)
+ go func() {
+ var tmp [1]byte
+ rp.Read(tmp[:])
+ <-done
+ wg.Done()
+ }()
+
+ runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
+
+ // Test timers.
+ timerDone := make(chan bool)
+ go func() {
+ time.Sleep(time.Millisecond)
+ timerDone <- true
+ }()
+ <-timerDone
+
+ // A bit of network.
+ ln, err := net.Listen("tcp", "127.0.0.1:0")
+ if err != nil {
+ t.Errorf("listen failed: %v", err)
+ return
+ }
+ defer ln.Close()
+ go func() {
+ c, err := ln.Accept()
+ if err != nil {
+ return
+ }
+ time.Sleep(time.Millisecond)
+ var buf [1]byte
+ c.Write(buf[:])
+ c.Close()
+ }()
+ c, err := net.Dial("tcp", ln.Addr().String())
+ if err != nil {
+ t.Errorf("dial failed: %v", err)
+ return
+ }
+ var tmp [1]byte
+ c.Read(tmp[:])
+ c.Close()
+
+ go func() {
+ runtime.Gosched()
+ select {}
+ }()
+
+ // Unblock helper goroutines and wait them to finish.
+ wp.Write(tmp[:])
+ wp.Write(tmp[:])
+ close(done)
+ wg.Wait()
+ }()
+
+ for i := 0; i < 3; i++ {
+ buf := new(bytes.Buffer)
+ if err := Start(buf); err != nil {
+ t.Fatalf("failed to start tracing: %v", err)
+ }
+ time.Sleep(time.Millisecond)
+ Stop()
+ saveTrace(t, buf, "TestTraceStressStartStop")
+ trace := buf.Bytes()
+ parseTrace(t, buf)
+ testBrokenTimestamps(t, trace)
+ }
+ <-outerDone
+}
+
+func TestTraceFutileWakeup(t *testing.T) {
+ if IsEnabled() {
+ t.Skip("skipping because -test.trace is set")
+ }
+ if goexperiment.ExecTracer2 {
+ t.Skip("skipping because this test is incompatible with the new tracer")
+ }
+ buf := new(bytes.Buffer)
+ if err := Start(buf); err != nil {
+ t.Fatalf("failed to start tracing: %v", err)
+ }
+
+ defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(8))
+ c0 := make(chan int, 1)
+ c1 := make(chan int, 1)
+ c2 := make(chan int, 1)
+ const procs = 2
+ var done sync.WaitGroup
+ done.Add(4 * procs)
+ for p := 0; p < procs; p++ {
+ const iters = 1e3
+ go func() {
+ for i := 0; i < iters; i++ {
+ runtime.Gosched()
+ c0 <- 0
+ }
+ done.Done()
+ }()
+ go func() {
+ for i := 0; i < iters; i++ {
+ runtime.Gosched()
+ <-c0
+ }
+ done.Done()
+ }()
+ go func() {
+ for i := 0; i < iters; i++ {
+ runtime.Gosched()
+ select {
+ case c1 <- 0:
+ case c2 <- 0:
+ }
+ }
+ done.Done()
+ }()
+ go func() {
+ for i := 0; i < iters; i++ {
+ runtime.Gosched()
+ select {
+ case <-c1:
+ case <-c2:
+ }
+ }
+ done.Done()
+ }()
+ }
+ done.Wait()
+
+ Stop()
+ saveTrace(t, buf, "TestTraceFutileWakeup")
+ events, _ := parseTrace(t, buf)
+ // Check that (1) trace does not contain EvFutileWakeup events and
+ // (2) there are no consecutive EvGoBlock/EvGCStart/EvGoBlock events
+ // (we call runtime.Gosched between all operations, so these would be futile wakeups).
+ gs := make(map[uint64]int)
+ for _, ev := range events {
+ switch ev.Type {
+ case trace.EvFutileWakeup:
+ t.Fatalf("found EvFutileWakeup event")
+ case trace.EvGoBlockSend, trace.EvGoBlockRecv, trace.EvGoBlockSelect:
+ if gs[ev.G] == 2 {
+ t.Fatalf("goroutine %v blocked on %v at %v right after start",
+ ev.G, trace.EventDescriptions[ev.Type].Name, ev.Ts)
+ }
+ if gs[ev.G] == 1 {
+ t.Fatalf("goroutine %v blocked on %v at %v while blocked",
+ ev.G, trace.EventDescriptions[ev.Type].Name, ev.Ts)
+ }
+ gs[ev.G] = 1
+ case trace.EvGoStart:
+ if gs[ev.G] == 1 {
+ gs[ev.G] = 2
+ }
+ default:
+ delete(gs, ev.G)
+ }
+ }
+}
+
+func TestTraceCPUProfile(t *testing.T) {
+ if IsEnabled() {
+ t.Skip("skipping because -test.trace is set")
+ }
+ if goexperiment.ExecTracer2 {
+ // An equivalent test exists in internal/trace/v2.
+ t.Skip("skipping because this test is incompatible with the new tracer")
+ }
+
+ cpuBuf := new(bytes.Buffer)
+ if err := pprof.StartCPUProfile(cpuBuf); err != nil {
+ t.Skipf("failed to start CPU profile: %v", err)
+ }
+
+ buf := new(bytes.Buffer)
+ if err := Start(buf); err != nil {
+ t.Fatalf("failed to start tracing: %v", err)
+ }
+
+ dur := 100 * time.Millisecond
+ func() {
+ // Create a region in the execution trace. Set and clear goroutine
+ // labels fully within that region, so we know that any CPU profile
+ // sample with the label must also be eligible for inclusion in the
+ // execution trace.
+ ctx := context.Background()
+ defer StartRegion(ctx, "cpuHogger").End()
+ pprof.Do(ctx, pprof.Labels("tracing", "on"), func(ctx context.Context) {
+ cpuHogger(cpuHog1, &salt1, dur)
+ })
+ // Be sure the execution trace's view, when filtered to this goroutine
+ // via the explicit goroutine ID in each event, gets many more samples
+ // than the CPU profiler when filtered to this goroutine via labels.
+ cpuHogger(cpuHog1, &salt1, dur)
+ }()
+
+ Stop()
+ pprof.StopCPUProfile()
+ saveTrace(t, buf, "TestTraceCPUProfile")
+
+ prof, err := profile.Parse(cpuBuf)
+ if err != nil {
+ t.Fatalf("failed to parse CPU profile: %v", err)
+ }
+ // Examine the CPU profiler's view. Filter it to only include samples from
+ // the single test goroutine. Use labels to execute that filter: they should
+ // apply to all work done while that goroutine is getg().m.curg, and they
+ // should apply to no other goroutines.
+ pprofSamples := 0
+ pprofStacks := make(map[string]int)
+ for _, s := range prof.Sample {
+ if s.Label["tracing"] != nil {
+ var fns []string
+ var leaf string
+ for _, loc := range s.Location {
+ for _, line := range loc.Line {
+ fns = append(fns, fmt.Sprintf("%s:%d", line.Function.Name, line.Line))
+ leaf = line.Function.Name
+ }
+ }
+ // runtime.sigprof synthesizes call stacks when "normal traceback is
+ // impossible or has failed", using particular placeholder functions
+ // to represent common failure cases. Look for those functions in
+ // the leaf position as a sign that the call stack and its
+ // symbolization are more complex than this test can handle.
+ //
+ // TODO: Make the symbolization done by the execution tracer and CPU
+ // profiler match up even in these harder cases. See #53378.
+ switch leaf {
+ case "runtime._System", "runtime._GC", "runtime._ExternalCode", "runtime._VDSO":
+ continue
+ }
+ stack := strings.Join(fns, " ")
+ samples := int(s.Value[0])
+ pprofSamples += samples
+ pprofStacks[stack] += samples
+ }
+ }
+ if pprofSamples == 0 {
+ t.Skipf("CPU profile did not include any samples while tracing was active\n%s", prof)
+ }
+
+ // Examine the execution tracer's view of the CPU profile samples. Filter it
+ // to only include samples from the single test goroutine. Use the goroutine
+ // ID that was recorded in the events: that should reflect getg().m.curg,
+ // same as the profiler's labels (even when the M is using its g0 stack).
+ totalTraceSamples := 0
+ traceSamples := 0
+ traceStacks := make(map[string]int)
+ events, _ := parseTrace(t, buf)
+ var hogRegion *trace.Event
+ for _, ev := range events {
+ if ev.Type == trace.EvUserRegion && ev.Args[1] == 0 && ev.SArgs[0] == "cpuHogger" {
+ // mode "0" indicates region start
+ hogRegion = ev
+ }
+ }
+ if hogRegion == nil {
+ t.Fatalf("execution trace did not identify cpuHogger goroutine")
+ } else if hogRegion.Link == nil {
+ t.Fatalf("execution trace did not close cpuHogger region")
+ }
+ for _, ev := range events {
+ if ev.Type == trace.EvCPUSample {
+ totalTraceSamples++
+ if ev.G == hogRegion.G {
+ traceSamples++
+ var fns []string
+ for _, frame := range ev.Stk {
+ if frame.Fn != "runtime.goexit" {
+ fns = append(fns, fmt.Sprintf("%s:%d", frame.Fn, frame.Line))
+ }
+ }
+ stack := strings.Join(fns, " ")
+ traceStacks[stack]++
+ }
+ }
+ }
+
+ // The execution trace may drop CPU profile samples if the profiling buffer
+ // overflows. Based on the size of profBufWordCount, that takes a bit over
+ // 1900 CPU samples or 19 thread-seconds at a 100 Hz sample rate. If we've
+ // hit that case, then we definitely have at least one full buffer's worth
+ // of CPU samples, so we'll call that success.
+ overflowed := totalTraceSamples >= 1900
+ if traceSamples < pprofSamples {
+ t.Logf("execution trace did not include all CPU profile samples; %d in profile, %d in trace", pprofSamples, traceSamples)
+ if !overflowed {
+ t.Fail()
+ }
+ }
+
+ for stack, traceSamples := range traceStacks {
+ pprofSamples := pprofStacks[stack]
+ delete(pprofStacks, stack)
+ if traceSamples < pprofSamples {
+ t.Logf("execution trace did not include all CPU profile samples for stack %q; %d in profile, %d in trace",
+ stack, pprofSamples, traceSamples)
+ if !overflowed {
+ t.Fail()
+ }
+ }
+ }
+ for stack, pprofSamples := range pprofStacks {
+ t.Logf("CPU profile included %d samples at stack %q not present in execution trace", pprofSamples, stack)
+ if !overflowed {
+ t.Fail()
+ }
+ }
+
+ if t.Failed() {
+ t.Logf("execution trace CPU samples:")
+ for stack, samples := range traceStacks {
+ t.Logf("%d: %q", samples, stack)
+ }
+ t.Logf("CPU profile:\n%v", prof)
+ }
+}
+
+func cpuHogger(f func(x int) int, y *int, dur time.Duration) {
+ // We only need to get one 100 Hz clock tick, so we've got
+ // a large safety buffer.
+ // But do at least 500 iterations (which should take about 100ms),
+ // otherwise TestCPUProfileMultithreaded can fail if only one
+ // thread is scheduled during the testing period.
+ t0 := time.Now()
+ accum := *y
+ for i := 0; i < 500 || time.Since(t0) < dur; i++ {
+ accum = f(accum)
+ }
+ *y = accum
+}
+
+var (
+ salt1 = 0
+)
+
+// The actual CPU hogging function.
+// Must not call other functions nor access heap/globals in the loop,
+// otherwise under race detector the samples will be in the race runtime.
+func cpuHog1(x int) int {
+ return cpuHog0(x, 1e5)
+}
+
+func cpuHog0(x, n int) int {
+ foo := x
+ for i := 0; i < n; i++ {
+ if i%1000 == 0 {
+ // Spend time in mcall, stored as gp.m.curg, with g0 running
+ runtime.Gosched()
+ }
+ if foo > 0 {
+ foo *= foo
+ } else {
+ foo *= foo + 1
+ }
+ }
+ return foo
+}
+
+func saveTrace(t *testing.T, buf *bytes.Buffer, name string) {
+ if !*saveTraces {
+ return
+ }
+ if err := os.WriteFile(name+".trace", buf.Bytes(), 0600); err != nil {
+ t.Errorf("failed to write trace file: %s", err)
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-28 23:39:12 +0000