Add enhanced vfsreadlat BCC example with live plotly and dash graphs on browser

BCC-Examples/vfsreadlat_plotly/bpf_program.py

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+"""BPF program for tracing VFS read latency."""
+
+from pythonbpf import bpf, map, struct, section, bpfglobal, BPF
+from pythonbpf.helper import ktime, pid
+from pythonbpf.maps import HashMap, PerfEventArray
+from ctypes import c_void_p, c_uint64
+import argparse
+from data_collector import LatencyCollector
+from dashboard import LatencyDashboard
+
+
+@bpf
+@struct
+class latency_event:
+    pid: c_uint64
+    delta_us: c_uint64
+
+
+@bpf
+@map
+def start() -> HashMap:
+    """Map to store start timestamps by PID."""
+    return HashMap(key=c_uint64, value=c_uint64, max_entries=10240)
+
+
+@bpf
+@map
+def events() -> PerfEventArray:
+    """Perf event array for sending latency events to userspace."""
+    return PerfEventArray(key_size=c_uint64, value_size=c_uint64)
+
+
+@bpf
+@section("kprobe/vfs_read")
+def do_entry(ctx: c_void_p) -> c_uint64:
+    """Record start time when vfs_read is called."""
+    p, ts = pid(), ktime()
+    start.update(p, ts)
+    return 0  # type: ignore [return-value]
+
+
+@bpf
+@section("kretprobe/vfs_read")
+def do_return(ctx: c_void_p) -> c_uint64:
+    """Calculate and record latency when vfs_read returns."""
+    p = pid()
+    tsp = start.lookup(p)
+
+    if tsp:
+        delta_ns = ktime() - tsp
+
+        # Only track latencies > 1 microsecond
+        if delta_ns > 1000:
+            evt = latency_event()
+            evt.pid, evt.delta_us = p, delta_ns // 1000
+            events.output(evt)
+
+        start.delete(p)
+
+    return 0  # type: ignore [return-value]
+
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+
+def parse_args():
+    """Parse command line arguments."""
+    parser = argparse.ArgumentParser(
+        description="Monitor VFS read latency with live dashboard"
+    )
+    parser.add_argument(
+        "--host", default="0.0.0.0", help="Dashboard host (default: 0.0.0.0)"
+    )
+    parser.add_argument(
+        "--port", type=int, default=8050, help="Dashboard port (default: 8050)"
+    )
+    parser.add_argument(
+        "--buffer", type=int, default=10000, help="Recent data buffer size"
+    )
+    return parser.parse_args()
+
+
+args = parse_args()
+
+# Load BPF program
+print("Loading BPF program...")
+b = BPF()
+b.load()
+b.attach_all()
+print("✅ BPF program loaded and attached")
+
+# Setup data collector
+collector = LatencyCollector(b, buffer_size=args.buffer)
+collector.start()
+
+# Create and run dashboard
+dashboard = LatencyDashboard(collector)
+dashboard.run(host=args.host, port=args.port)