91 lines
2.1 KiB
C
91 lines
2.1 KiB
C
/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of version 2 of the GNU General Public
|
|
* License as published by the Free Software Foundation.
|
|
*/
|
|
#include <linux/skbuff.h>
|
|
#include <linux/netdevice.h>
|
|
#include <linux/version.h>
|
|
#include <uapi/linux/bpf.h>
|
|
#include "bpf_helpers.h"
|
|
#include "bpf_tracing.h"
|
|
|
|
struct bpf_map_def SEC("maps") my_map = {
|
|
.type = BPF_MAP_TYPE_HASH,
|
|
.key_size = sizeof(long),
|
|
.value_size = sizeof(u64),
|
|
.max_entries = 4096,
|
|
};
|
|
|
|
/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
|
|
* example will no longer be meaningful
|
|
*/
|
|
SEC("kprobe/blk_mq_start_request")
|
|
int bpf_prog1(struct pt_regs *ctx)
|
|
{
|
|
long rq = PT_REGS_PARM1(ctx);
|
|
u64 val = bpf_ktime_get_ns();
|
|
|
|
bpf_map_update_elem(&my_map, &rq, &val, BPF_ANY);
|
|
return 0;
|
|
}
|
|
|
|
static unsigned int log2l(unsigned long long n)
|
|
{
|
|
#define S(k) if (n >= (1ull << k)) { i += k; n >>= k; }
|
|
int i = -(n == 0);
|
|
S(32); S(16); S(8); S(4); S(2); S(1);
|
|
return i;
|
|
#undef S
|
|
}
|
|
|
|
#define SLOTS 100
|
|
|
|
struct bpf_map_def SEC("maps") lat_map = {
|
|
.type = BPF_MAP_TYPE_PERCPU_ARRAY,
|
|
.key_size = sizeof(u32),
|
|
.value_size = sizeof(u64),
|
|
.max_entries = SLOTS,
|
|
};
|
|
|
|
SEC("kprobe/blk_account_io_completion")
|
|
int bpf_prog2(struct pt_regs *ctx)
|
|
{
|
|
long rq = PT_REGS_PARM1(ctx);
|
|
u64 *value, l, base;
|
|
u32 index;
|
|
|
|
value = bpf_map_lookup_elem(&my_map, &rq);
|
|
if (!value)
|
|
return 0;
|
|
|
|
u64 cur_time = bpf_ktime_get_ns();
|
|
u64 delta = cur_time - *value;
|
|
|
|
bpf_map_delete_elem(&my_map, &rq);
|
|
|
|
/* the lines below are computing index = log10(delta)*10
|
|
* using integer arithmetic
|
|
* index = 29 ~ 1 usec
|
|
* index = 59 ~ 1 msec
|
|
* index = 89 ~ 1 sec
|
|
* index = 99 ~ 10sec or more
|
|
* log10(x)*10 = log2(x)*10/log2(10) = log2(x)*3
|
|
*/
|
|
l = log2l(delta);
|
|
base = 1ll << l;
|
|
index = (l * 64 + (delta - base) * 64 / base) * 3 / 64;
|
|
|
|
if (index >= SLOTS)
|
|
index = SLOTS - 1;
|
|
|
|
value = bpf_map_lookup_elem(&lat_map, &index);
|
|
if (value)
|
|
*value += 1;
|
|
|
|
return 0;
|
|
}
|
|
char _license[] SEC("license") = "GPL";
|
|
u32 _version SEC("version") = LINUX_VERSION_CODE;
|