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