| #!/usr/bin/python |
| # @lint-avoid-python-3-compatibility-imports |
| # |
| # 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. |
| # 11-Feb-2016 Allan McAleavy updated for BPF_PERF_OUTPUT |
| |
| from __future__ import print_function |
| from bcc import BPF |
| import ctypes as ct |
| import re |
| |
| # load BPF program |
| b = BPF(text=""" |
| #include <uapi/linux/ptrace.h> |
| #include <linux/blkdev.h> |
| |
| struct val_t { |
| u32 pid; |
| char name[TASK_COMM_LEN]; |
| }; |
| |
| struct data_t { |
| u32 pid; |
| u64 rwflag; |
| u64 delta; |
| u64 sector; |
| u64 len; |
| u64 ts; |
| char disk_name[DISK_NAME_LEN]; |
| char name[TASK_COMM_LEN]; |
| }; |
| |
| BPF_HASH(start, struct request *); |
| BPF_HASH(infobyreq, struct request *, struct val_t); |
| BPF_PERF_OUTPUT(events); |
| |
| // cache PID and comm by-req |
| int trace_pid_start(struct pt_regs *ctx, struct request *req) |
| { |
| struct val_t val = {}; |
| |
| if (bpf_get_current_comm(&val.name, sizeof(val.name)) == 0) { |
| val.pid = bpf_get_current_pid_tgid(); |
| infobyreq.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; |
| struct data_t data = {}; |
| u64 ts; |
| |
| // fetch timestamp and calculate delta |
| tsp = start.lookup(&req); |
| if (tsp == 0) { |
| // missed tracing issue |
| return 0; |
| } |
| ts = bpf_ktime_get_ns(); |
| data.delta = ts - *tsp; |
| data.ts = ts / 1000; |
| |
| valp = infobyreq.lookup(&req); |
| if (valp == 0) { |
| data.len = req->__data_len; |
| strcpy(data.name, "?"); |
| } else { |
| data.pid = valp->pid; |
| data.len = req->__data_len; |
| data.sector = req->__sector; |
| bpf_probe_read(&data.name, sizeof(data.name), valp->name); |
| bpf_probe_read(&data.disk_name, sizeof(data.disk_name), |
| req->rq_disk->disk_name); |
| } |
| |
| /* |
| * The following deals with a kernel version change (in mainline 4.7, although |
| * it may be backported to earlier kernels) with how block request write flags |
| * are tested. We handle both pre- and post-change versions here. Please avoid |
| * kernel version tests like this as much as possible: they inflate the code, |
| * test, and maintenance burden. |
| */ |
| #ifdef REQ_WRITE |
| data.rwflag = !!(req->cmd_flags & REQ_WRITE); |
| #elif defined(REQ_OP_SHIFT) |
| data.rwflag = !!((req->cmd_flags >> REQ_OP_SHIFT) == REQ_OP_WRITE); |
| #else |
| data.rwflag = !!((req->cmd_flags & REQ_OP_MASK) == REQ_OP_WRITE); |
| #endif |
| |
| events.perf_submit(ctx, &data, sizeof(data)); |
| start.delete(&req); |
| infobyreq.delete(&req); |
| |
| return 0; |
| } |
| """, debug=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") |
| |
| TASK_COMM_LEN = 16 # linux/sched.h |
| DISK_NAME_LEN = 32 # linux/genhd.h |
| |
| class Data(ct.Structure): |
| _fields_ = [ |
| ("pid", ct.c_ulonglong), |
| ("rwflag", ct.c_ulonglong), |
| ("delta", ct.c_ulonglong), |
| ("sector", ct.c_ulonglong), |
| ("len", ct.c_ulonglong), |
| ("ts", ct.c_ulonglong), |
| ("disk_name", ct.c_char * DISK_NAME_LEN), |
| ("name", ct.c_char * TASK_COMM_LEN) |
| ] |
| |
| # header |
| print("%-14s %-14s %-6s %-7s %-2s %-9s %-7s %7s" % ("TIME(s)", "COMM", "PID", |
| "DISK", "T", "SECTOR", "BYTES", "LAT(ms)")) |
| |
| rwflg = "" |
| start_ts = 0 |
| prev_ts = 0 |
| delta = 0 |
| |
| # process event |
| def print_event(cpu, data, size): |
| event = ct.cast(data, ct.POINTER(Data)).contents |
| |
| val = -1 |
| global start_ts |
| global prev_ts |
| global delta |
| |
| if event.rwflag == 1: |
| rwflg = "W" |
| |
| if event.rwflag == 0: |
| rwflg = "R" |
| |
| if not re.match(b'\?', event.name): |
| val = event.sector |
| |
| if start_ts == 0: |
| prev_ts = start_ts |
| |
| if start_ts == 1: |
| delta = float(delta) + (event.ts - prev_ts) |
| |
| print("%-14.9f %-14.14s %-6s %-7s %-2s %-9s %-7s %7.2f" % ( |
| delta / 1000000, event.name, event.pid, event.disk_name, rwflg, val, |
| event.len, float(event.delta) / 1000000)) |
| |
| prev_ts = event.ts |
| start_ts = 1 |
| |
| # loop with callback to print_event |
| b["events"].open_perf_buffer(print_event) |
| while 1: |
| b.kprobe_poll() |