mirror of
https://github.com/varun-r-mallya/Python-BPF.git
synced 2025-12-31 21:06:25 +00:00
67 lines
1.8 KiB
C
67 lines
1.8 KiB
C
// disksnoop.bpf.c
|
|
// eBPF program (compile with: clang -O2 -g -target bpf -c disksnoop.bpf.c -o disksnoop.bpf.o)
|
|
|
|
#include "vmlinux.h"
|
|
#include <bpf/bpf_helpers.h>
|
|
#include <bpf/bpf_core_read.h>
|
|
|
|
char LICENSE[] SEC("license") = "GPL";
|
|
|
|
struct {
|
|
__uint(type, BPF_MAP_TYPE_HASH);
|
|
__type(key, __u64);
|
|
__type(value, __u64);
|
|
__uint(max_entries, 10240);
|
|
} start_map SEC(".maps");
|
|
|
|
/* kprobe: record start timestamp keyed by request pointer */
|
|
SEC("kprobe/blk_mq_start_request")
|
|
int trace_start(struct pt_regs *ctx)
|
|
{
|
|
/* request * is first arg */
|
|
__u64 reqp = (__u64)(ctx->di);
|
|
__u64 ts = bpf_ktime_get_ns();
|
|
|
|
bpf_map_update_elem(&start_map, &reqp, &ts, BPF_ANY);
|
|
|
|
// /* optional debug:
|
|
bpf_printk("start: req=%llu ts=%llu\n", reqp, ts);
|
|
// */
|
|
return 0;
|
|
}
|
|
|
|
/* completion: compute latency and print data_len, cmd_flags, latency_us */
|
|
SEC("kprobe/blk_mq_end_request")
|
|
int trace_completion(struct pt_regs *ctx)
|
|
{
|
|
__u64 reqp = (__u64)(ctx->di);
|
|
__u64 *tsp;
|
|
__u64 now_ns;
|
|
__u64 delta_ns;
|
|
__u64 delta_us = 0;
|
|
bpf_printk("%lld", reqp);
|
|
tsp = bpf_map_lookup_elem(&start_map, &reqp);
|
|
if (!tsp)
|
|
return 0;
|
|
|
|
now_ns = bpf_ktime_get_ns();
|
|
delta_ns = now_ns - *tsp;
|
|
delta_us = delta_ns / 1000;
|
|
|
|
/* read request fields using CO-RE; needs vmlinux.h/BTF */
|
|
__u32 data_len = 0;
|
|
__u32 cmd_flags = 0;
|
|
|
|
/* __data_len is usually a 32/64-bit; use CORE read to be safe */
|
|
data_len = ( __u32 ) BPF_CORE_READ((struct request *)reqp, __data_len);
|
|
cmd_flags = ( __u32 ) BPF_CORE_READ((struct request *)reqp, cmd_flags);
|
|
|
|
/* print: "<bytes> <flags_hex> <latency_us>" */
|
|
bpf_printk("%u %x %llu\n", data_len, cmd_flags, delta_us);
|
|
|
|
/* remove from map */
|
|
bpf_map_delete_elem(&start_map, &reqp);
|
|
|
|
return 0;
|
|
}
|