diff --git a/tools/biosnoop b/tools/biosnoop
new file mode 100755
index 0000000..43484dd
--- /dev/null
+++ b/tools/biosnoop
@@ -0,0 +1,133 @@
+#!/usr/bin/python
+#
+# biosnoop	Trace block device I/O and print details including issuing PID.
+#		For Linux, uses BCC, eBPF.
+#
+# This uses in-kernel eBPF maps to cache process details (PID and comm) by I/O
+# request, as well as a starting timestamp for calculating I/O latency.
+#
+# Copyright (c) 2015 Brendan Gregg.
+# Licensed under the Apache License, Version 2.0 (the "License")
+#
+# 16-Sep-2015	Brendan Gregg	Created this.
+
+from __future__ import print_function
+from bcc import BPF
+
+# load BPF program
+b = BPF(text="""
+#include <uapi/linux/ptrace.h>
+#include <linux/blkdev.h>
+
+struct val_t {
+	char name[TASK_COMM_LEN];
+};
+
+BPF_HASH(start, struct request *);
+BPF_HASH(pidbyreq, struct request *, u32);
+BPF_HASH(commbyreq, struct request *, struct val_t);
+
+// cache PID and comm by-req
+int trace_pid_start(struct pt_regs *ctx, struct request *req)
+{
+	u32 pid;
+	struct val_t val = {};
+
+	pid = bpf_get_current_pid_tgid();
+	pidbyreq.update(&req, &pid);
+	if (bpf_get_current_comm(&val.name, sizeof(val.name)) == 0) {
+		commbyreq.update(&req, &val);
+	}
+
+	return 0;
+}
+
+// time block I/O
+int trace_req_start(struct pt_regs *ctx, struct request *req)
+{
+	u64 ts;
+
+	ts = bpf_ktime_get_ns();
+	start.update(&req, &ts);
+
+	return 0;
+}
+
+// output
+int trace_req_completion(struct pt_regs *ctx, struct request *req)
+{
+	u64 *tsp, delta;
+	u32 *pidp = 0;
+	struct val_t *valp;
+
+	// fetch timestamp and calculate delta
+	tsp = start.lookup(&req);
+	if (tsp == 0) {
+		// missed tracing issue
+		return 0;
+	}
+	delta = bpf_ktime_get_ns() - *tsp;
+
+	//
+	// Fetch and output issuing pid and comm.
+	// As bpf_trace_prink() is limited to a maximum of 1 string and 2
+	// integers, we'll use more than one to output the data.
+	//
+	valp = commbyreq.lookup(&req);
+	pidp = pidbyreq.lookup(&req);
+	if (pidp == 0 || valp == 0) {
+		bpf_trace_printk("0 0 ? %d\\n", req->__data_len);
+	} else {
+		bpf_trace_printk("0 %d %s %d\\n", *pidp, valp->name,
+		    req->__data_len);
+	}
+
+	// output remaining details
+	if (req->cmd_flags & REQ_WRITE) {
+		bpf_trace_printk("1 W %s %d %d ?\\n", req->rq_disk->disk_name,
+		    req->__sector, delta / 1000);
+	} else {
+		bpf_trace_printk("1 R %s %d %d ?\\n", req->rq_disk->disk_name,
+		    req->__sector, delta / 1000);
+	}
+
+	start.delete(&req);
+	pidbyreq.delete(&req);
+	commbyreq.delete(&req);
+
+	return 0;
+}
+""")
+# blk_account_io_start is chosen to be as
+b.attach_kprobe(event="blk_account_io_start", fn_name="trace_pid_start")
+b.attach_kprobe(event="blk_start_request", fn_name="trace_req_start")
+b.attach_kprobe(event="blk_mq_start_request", fn_name="trace_req_start")
+b.attach_kprobe(event="blk_account_io_completion",
+    fn_name="trace_req_completion")
+
+# header
+print("%-14s %-14s %-6s %-7s %-2s %-9s %-7s %7s" % ("TIME(s)", "COMM", "PID",
+    "DISK", "T", "SECTOR", "BYTES", "LAT(ms)"))
+
+start_ts = 0
+
+# format output
+while 1:
+	(task, pid, cpu, flags, ts, msg) = b.trace_fields()
+	args = msg.split(" ")
+
+	if start_ts == 0:
+		start_ts = ts
+
+	if args[0] == "0":
+		(real_pid, real_comm, bytes_s) = (args[1], args[2], args[3])
+		continue
+	else:
+		(type_s, disk_s, sector_s, us_s) = (args[1], args[2], args[3],
+		    args[4])
+
+	ms = float(int(us_s, 10)) / 1000
+
+	print("%-14.9f %-14.14s %-6s %-7s %-2s %-9s %-7s %7.2f" % (
+	    ts - start_ts, real_comm, real_pid, disk_s, type_s, sector_s,
+	    bytes_s, ms))