Commit 64c28817 authored by Brendan Gregg's avatar Brendan Gregg Committed by GitHub

Merge pull request #655 from markdrayton/dcsnoop

dcsnoop: use PERF_EVENT_OUTPUT
parents e2a8290c 00789366
......@@ -23,7 +23,9 @@
from __future__ import print_function
from bcc import BPF
import argparse
import ctypes as ct
import re
import time
# arguments
examples = """examples:
......@@ -46,12 +48,26 @@ bpf_text = """
#define MAX_FILE_LEN 64
enum lookup_type {
LOOKUP_MISS,
LOOKUP_REFERENCE,
};
struct entry_t {
char name[MAX_FILE_LEN];
};
BPF_HASH(entrybypid, u32, struct entry_t);
struct data_t {
u32 pid;
enum lookup_type type;
char comm[TASK_COMM_LEN];
char filename[MAX_FILE_LEN];
};
BPF_PERF_OUTPUT(events);
/* from fs/namei.c: */
struct nameidata {
struct path path;
......@@ -59,9 +75,22 @@ struct nameidata {
// [...]
};
static inline
void submit_event(struct pt_regs *ctx, void *name, int type, u32 pid)
{
struct data_t data = {
.pid = pid,
.type = type,
};
bpf_get_current_comm(&data.comm, sizeof(data.comm));
bpf_probe_read(&data.filename, sizeof(data.filename), name);
events.perf_submit(ctx, &data, sizeof(data));
}
int trace_fast(struct pt_regs *ctx, struct nameidata *nd, struct path *path)
{
bpf_trace_printk("R %s\\n", nd->last.name);
u32 pid = bpf_get_current_pid_tgid();
submit_event(ctx, (void *)nd->last.name, LOOKUP_REFERENCE, pid);
return 1;
}
......@@ -83,36 +112,47 @@ int kretprobe__d_lookup(struct pt_regs *ctx)
u32 pid = bpf_get_current_pid_tgid();
struct entry_t *ep;
ep = entrybypid.lookup(&pid);
if (ep == 0) {
return 0; // missed entry
}
if (PT_REGS_RC(ctx) == 0) {
bpf_trace_printk("M %s\\n", ep->name);
if (ep == 0 || PT_REGS_RC(ctx) != 0) {
return 0; // missed entry or lookup didn't fail
}
submit_event(ctx, (void *)ep->name, LOOKUP_MISS, pid);
entrybypid.delete(&pid);
return 0;
}
"""
TASK_COMM_LEN = 16 # linux/sched.h
MAX_FILE_LEN = 64 # see inline C
class Data(ct.Structure):
_fields_ = [
("pid", ct.c_uint),
("type", ct.c_int),
("comm", ct.c_char * TASK_COMM_LEN),
("filename", ct.c_char * MAX_FILE_LEN),
]
# initialize BPF
b = BPF(text=bpf_text)
if args.all:
b.attach_kprobe(event="lookup_fast", fn_name="trace_fast")
# header
print("%-11s %-6s %-16s %1s %s" % ("TIME(s)", "PID", "COMM", "T", "FILE"))
mode_s = {
0: 'M',
1: 'R',
}
start_ts = 0
start_ts = time.time()
# format output
while 1:
(task, pid, cpu, flags, ts, msg) = b.trace_fields()
try:
(type, file) = msg.split(" ", 1)
except ValueError:
continue
def print_event(cpu, data, size):
event = ct.cast(data, ct.POINTER(Data)).contents
print("%-11.6f %-6d %-16s %1s %s" % (
time.time() - start_ts, event.pid, event.comm, mode_s[event.type],
event.filename))
if start_ts == 0:
start_ts = ts
# header
print("%-11s %-6s %-16s %1s %s" % ("TIME(s)", "PID", "COMM", "T", "FILE"))
print("%-11.6f %-6s %-16s %1s %s" % (ts - start_ts, pid, task, type, file))
b["events"].open_perf_buffer(print_event)
while 1:
b.kprobe_poll()
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