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Copy pathbiosnoop
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executable file
·132 lines (109 loc) · 3.18 KB
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#!/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;
}
""")
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))