generate perf event data structure in Python automatically (#2198)
* generate perf event data structure in Python automatically
When ring buffers are opened to receive custom perf event, we have
to define the event data structure twice: once in BPF C and once
in Python. It is tedious and error-prone.
This patch implements the automatic generation of Python data structure
from the C declaration, thus making the redundant definition in Python
unnecessary. Example:
// define output data structure in C
struct data_t {
u32 pid;
u64 ts;
char comm[TASK_COMM_LEN];
};
BPF_PERF_OUTPUT(events);
...
Old way:
# define output data structure in Python
TASK_COMM_LEN = 16 # linux/sched.h
class Data(ct.Structure):
_fields_ = [("pid", ct.c_ulonglong),
("ts", ct.c_ulonglong),
("comm", ct.c_char * TASK_COMM_LEN)]
def print_event(cpu, data, size):
event = ct.cast(data, ct.POINTER(Data)).contents
...
New way:
def print_event(cpu, data, size):
event = b["events"].event(data)
...
* tools/tcpconnect.py: deduce perf event data structure automatically
Take tcpconnect.py as an example to show the new, simpler way
of outputing perf event.
Other tools/examples can be simplified in a similar way.
diff --git a/tools/tcpconnect.py b/tools/tcpconnect.py
index 54364c9..e230f65 100755
--- a/tools/tcpconnect.py
+++ b/tools/tcpconnect.py
@@ -24,7 +24,6 @@
import argparse
from socket import inet_ntop, ntohs, AF_INET, AF_INET6
from struct import pack
-import ctypes as ct
# arguments
examples = """examples:
@@ -187,36 +186,9 @@
if args.ebpf:
exit()
-# event data
-TASK_COMM_LEN = 16 # linux/sched.h
-
-class Data_ipv4(ct.Structure):
- _fields_ = [
- ("ts_us", ct.c_ulonglong),
- ("pid", ct.c_uint),
- ("uid", ct.c_uint),
- ("saddr", ct.c_uint),
- ("daddr", ct.c_uint),
- ("ip", ct.c_ulonglong),
- ("dport", ct.c_ushort),
- ("task", ct.c_char * TASK_COMM_LEN)
- ]
-
-class Data_ipv6(ct.Structure):
- _fields_ = [
- ("ts_us", ct.c_ulonglong),
- ("pid", ct.c_uint),
- ("uid", ct.c_uint),
- ("saddr", (ct.c_ulonglong * 2)),
- ("daddr", (ct.c_ulonglong * 2)),
- ("ip", ct.c_ulonglong),
- ("dport", ct.c_ushort),
- ("task", ct.c_char * TASK_COMM_LEN)
- ]
-
# process event
def print_ipv4_event(cpu, data, size):
- event = ct.cast(data, ct.POINTER(Data_ipv4)).contents
+ event = b["ipv4_events"].event(data)
global start_ts
if args.timestamp:
if start_ts == 0:
@@ -230,7 +202,7 @@
inet_ntop(AF_INET, pack("I", event.daddr)).encode(), event.dport))
def print_ipv6_event(cpu, data, size):
- event = ct.cast(data, ct.POINTER(Data_ipv6)).contents
+ event = b["ipv6_events"].event(data)
global start_ts
if args.timestamp:
if start_ts == 0: