1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
|
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
*
* Authors: Waiman Long <longman@redhat.com>
*/
#include "lock_events.h"
#ifdef CONFIG_LOCK_EVENT_COUNTS
#ifdef CONFIG_PARAVIRT_SPINLOCKS
/*
* Collect pvqspinlock locking event counts
*/
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/fs.h>
#define EVENT_COUNT(ev) lockevents[LOCKEVENT_ ## ev]
/*
* PV specific per-cpu counter
*/
static DEFINE_PER_CPU(u64, pv_kick_time);
/*
* Function to read and return the PV qspinlock counts.
*
* The following counters are handled specially:
* 1. pv_latency_kick
* Average kick latency (ns) = pv_latency_kick/pv_kick_unlock
* 2. pv_latency_wake
* Average wake latency (ns) = pv_latency_wake/pv_kick_wake
* 3. pv_hash_hops
* Average hops/hash = pv_hash_hops/pv_kick_unlock
*/
ssize_t lockevent_read(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
char buf[64];
int cpu, id, len;
u64 sum = 0, kicks = 0;
/*
* Get the counter ID stored in file->f_inode->i_private
*/
id = (long)file_inode(file)->i_private;
if (id >= lockevent_num)
return -EBADF;
for_each_possible_cpu(cpu) {
sum += per_cpu(lockevents[id], cpu);
/*
* Need to sum additional counters for some of them
*/
switch (id) {
case LOCKEVENT_pv_latency_kick:
case LOCKEVENT_pv_hash_hops:
kicks += per_cpu(EVENT_COUNT(pv_kick_unlock), cpu);
break;
case LOCKEVENT_pv_latency_wake:
kicks += per_cpu(EVENT_COUNT(pv_kick_wake), cpu);
break;
}
}
if (id == LOCKEVENT_pv_hash_hops) {
u64 frac = 0;
if (kicks) {
frac = 100ULL * do_div(sum, kicks);
frac = DIV_ROUND_CLOSEST_ULL(frac, kicks);
}
/*
* Return a X.XX decimal number
*/
len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n",
sum, frac);
} else {
/*
* Round to the nearest ns
*/
if ((id == LOCKEVENT_pv_latency_kick) ||
(id == LOCKEVENT_pv_latency_wake)) {
if (kicks)
sum = DIV_ROUND_CLOSEST_ULL(sum, kicks);
}
len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum);
}
return simple_read_from_buffer(user_buf, count, ppos, buf, len);
}
/*
* PV hash hop count
*/
static inline void lockevent_pv_hop(int hopcnt)
{
this_cpu_add(EVENT_COUNT(pv_hash_hops), hopcnt);
}
/*
* Replacement function for pv_kick()
*/
static inline void __pv_kick(int cpu)
{
u64 start = sched_clock();
per_cpu(pv_kick_time, cpu) = start;
pv_kick(cpu);
this_cpu_add(EVENT_COUNT(pv_latency_kick), sched_clock() - start);
}
/*
* Replacement function for pv_wait()
*/
static inline void __pv_wait(u8 *ptr, u8 val)
{
u64 *pkick_time = this_cpu_ptr(&pv_kick_time);
*pkick_time = 0;
pv_wait(ptr, val);
if (*pkick_time) {
this_cpu_add(EVENT_COUNT(pv_latency_wake),
sched_clock() - *pkick_time);
lockevent_inc(pv_kick_wake);
}
}
#define pv_kick(c) __pv_kick(c)
#define pv_wait(p, v) __pv_wait(p, v)
#endif /* CONFIG_PARAVIRT_SPINLOCKS */
#else /* CONFIG_LOCK_EVENT_COUNTS */
static inline void lockevent_pv_hop(int hopcnt) { }
#endif /* CONFIG_LOCK_EVENT_COUNTS */
|
