Fix event comm attribution and reduce integration log noise

4 files changed, 71 insertions, 1 deletions

diff --git a/Magefile.go b/Magefile.go
index 7e88141..86e5958 100644
--- a/Magefile.go
+++ b/Magefile.go
@@ -672,14 +672,43 @@ func envToList(env map[string]string) []string {
 }
 
 func shouldPrintTestLog(msg string) bool {
+	// Always keep error/failure lines.
+	if strings.Contains(msg, "--- FAIL:") ||
+		strings.Contains(msg, " FAIL ") ||
+		strings.Contains(msg, "panic:") ||
+		strings.Contains(strings.ToLower(msg), "error") ||
+		strings.Contains(strings.ToLower(msg), "expected event not found") {
+		return true
+	}
+
 	// Drop high-volume attach/debug noise from ior startup in integration tests.
 	noisePrefixes := []string{
+		"=== RUN",
+		"___",
+		"|_ _|",
+		"| |",
+		"|___",
+		"v0.0.0",
+		"libbpf:",
 		"ShouldIAttachTracepoint called with ",
 		"Attaching tracepoint ",
 		"Attached prog handle_ ",
 		"Attached tracepoint",
 		"Attaching sys_",
 		"Not attaching sys_",
+		"Collecting flame graph stats",
+		"Starting flamegraph worker",
+		"Waiting for stats to be ready",
+		"Stopping event loop",
+		"Waiting for flamegraph",
+		"Worker ",
+		"Writing ",
+		"Good bye...",
+		"Statistics:",
+		"duration:",
+		"tracepoints:",
+		"syscalls:",
+		"syscalls after filter:",
 	}
 	for _, p := range noisePrefixes {
 		if strings.HasPrefix(msg, p) {
diff --git a/integrationtests/close_test.go b/integrationtests/close_test.go
index f2ecd34..3689fb8 100644
--- a/integrationtests/close_test.go
+++ b/integrationtests/close_test.go
@@ -28,6 +28,7 @@ func TestCloseInvalidFd(t *testing.T) {
 	runScenario(t, "close-invalid-fd", []ExpectedEvent{
 		{
 			Tracepoint: "enter_close",
+			Comm:       "ioworkload",
 			MinCount:   1,
 		},
 	})
diff --git a/integrationtests/cmd/ioworkload/scenario_copy_file_range.go b/integrationtests/cmd/ioworkload/scenario_copy_file_range.go
index 87531b0..ce0524e 100644
--- a/integrationtests/cmd/ioworkload/scenario_copy_file_range.go
+++ b/integrationtests/cmd/ioworkload/scenario_copy_file_range.go
@@ -37,6 +37,9 @@ func copyFileRangeBasic() error {
 	if _, err := syscall.Write(srcFd, data); err != nil {
 		return fmt.Errorf("write source: %w", err)
 	}
+	if _, err := syscall.Seek(srcFd, 0, 0); err != nil {
+		return fmt.Errorf("seek source: %w", err)
+	}
 
 	n, _, errno := syscall.Syscall6(uintptr(sysCopyFileRange), uintptr(srcFd), 0, uintptr(dstFd), 0, uintptr(len(data)), 0)
 	if errno != 0 {
diff --git a/internal/eventloop.go b/internal/eventloop.go
index 7bfd576..654d0fc 100644
--- a/internal/eventloop.go
+++ b/internal/eventloop.go
@@ -40,7 +40,7 @@ type eventLoop struct {
 }
 
 func newEventLoop() *eventLoop {
-	return &eventLoop{
+	el := &eventLoop{
 		filter:         newEventFilter(),
 		enterEvs:       make(map[uint32]*event.Pair),
 		pendingHandles: make(map[uint32]string),
@@ -51,6 +51,28 @@ func newEventLoop() *eventLoop {
 		flamegraph:     flamegraph.New(),
 		done:           make(chan struct{}),
 	}
+	el.seedTrackedPidComm()
+	return el
+}
+
+func (e *eventLoop) seedTrackedPidComm() {
+	pid := flags.Get().PidFilter
+	if pid <= 0 {
+		return
+	}
+	commPath := fmt.Sprintf("/proc/%d/comm", pid)
+	data, err := os.ReadFile(commPath)
+	if err != nil {
+		return
+	}
+	comm := string(data)
+	if len(comm) > 0 && comm[len(comm)-1] == '\n' {
+		comm = comm[:len(comm)-1]
+	}
+	if comm == "" {
+		return
+	}
+	e.comms[uint32(pid)] = comm
 }
 
 func (e *eventLoop) stats() string {
@@ -174,6 +196,10 @@ func (e *eventLoop) processRawEvent(raw []byte, ch chan<- *event.Pair) {
 
 func (e *eventLoop) tracepointEntered(enterEv event.Event) {
 	tid := enterEv.GetTid()
+	// Cache comm as early as possible to reduce races for short-lived processes.
+	if _, ok := e.comms[tid]; !ok {
+		_ = e.comm(tid)
+	}
 	if !e.filter.commFilterEnable {
 		e.enterEvs[tid] = event.NewPair(enterEv)
 		return
@@ -427,6 +453,17 @@ func (e *eventLoop) comm(tid uint32) string {
 	if comm, ok := e.comms[tid]; ok {
 		return comm
 	}
+	commPath := fmt.Sprintf("/proc/%d/comm", tid)
+	if data, err := os.ReadFile(commPath); err == nil {
+		comm := string(data)
+		if len(comm) > 0 && comm[len(comm)-1] == '\n' {
+			comm = comm[:len(comm)-1]
+		}
+		if comm != "" {
+			e.comms[tid] = comm
+			return comm
+		}
+	}
 	if linkName, err := os.Readlink(fmt.Sprintf("/proc/%d/exe", tid)); err == nil {
 		linkName = filepath.Base(linkName)
 		e.comms[tid] = linkName