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45e898b7 WL |
1 | /* |
2 | * This program is free software; you can redistribute it and/or modify | |
3 | * it under the terms of the GNU General Public License as published by | |
4 | * the Free Software Foundation; either version 2 of the License, or | |
5 | * (at your option) any later version. | |
6 | * | |
7 | * This program is distributed in the hope that it will be useful, | |
8 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
9 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
10 | * GNU General Public License for more details. | |
11 | * | |
fb346fd9 | 12 | * Authors: Waiman Long <longman@redhat.com> |
45e898b7 WL |
13 | */ |
14 | ||
ad53fa10 | 15 | #include "lock_events.h" |
45e898b7 | 16 | |
fb346fd9 WL |
17 | #ifdef CONFIG_LOCK_EVENT_COUNTS |
18 | #ifdef CONFIG_PARAVIRT_SPINLOCKS | |
45e898b7 | 19 | /* |
fb346fd9 | 20 | * Collect pvqspinlock locking event counts |
45e898b7 | 21 | */ |
45e898b7 | 22 | #include <linux/sched.h> |
e6017571 | 23 | #include <linux/sched/clock.h> |
45e898b7 WL |
24 | #include <linux/fs.h> |
25 | ||
ad53fa10 WL |
26 | #define EVENT_COUNT(ev) lockevents[LOCKEVENT_ ## ev] |
27 | ||
45e898b7 | 28 | /* |
fb346fd9 | 29 | * PV specific per-cpu counter |
45e898b7 | 30 | */ |
45e898b7 WL |
31 | static DEFINE_PER_CPU(u64, pv_kick_time); |
32 | ||
33 | /* | |
fb346fd9 | 34 | * Function to read and return the PV qspinlock counts. |
45e898b7 WL |
35 | * |
36 | * The following counters are handled specially: | |
ad53fa10 | 37 | * 1. pv_latency_kick |
45e898b7 | 38 | * Average kick latency (ns) = pv_latency_kick/pv_kick_unlock |
ad53fa10 | 39 | * 2. pv_latency_wake |
45e898b7 | 40 | * Average wake latency (ns) = pv_latency_wake/pv_kick_wake |
ad53fa10 | 41 | * 3. pv_hash_hops |
45e898b7 WL |
42 | * Average hops/hash = pv_hash_hops/pv_kick_unlock |
43 | */ | |
fb346fd9 WL |
44 | ssize_t lockevent_read(struct file *file, char __user *user_buf, |
45 | size_t count, loff_t *ppos) | |
45e898b7 WL |
46 | { |
47 | char buf[64]; | |
ad53fa10 WL |
48 | int cpu, id, len; |
49 | u64 sum = 0, kicks = 0; | |
45e898b7 WL |
50 | |
51 | /* | |
52 | * Get the counter ID stored in file->f_inode->i_private | |
53 | */ | |
ad53fa10 | 54 | id = (long)file_inode(file)->i_private; |
45e898b7 | 55 | |
ad53fa10 | 56 | if (id >= lockevent_num) |
45e898b7 WL |
57 | return -EBADF; |
58 | ||
59 | for_each_possible_cpu(cpu) { | |
ad53fa10 | 60 | sum += per_cpu(lockevents[id], cpu); |
45e898b7 | 61 | /* |
ad53fa10 | 62 | * Need to sum additional counters for some of them |
45e898b7 | 63 | */ |
ad53fa10 | 64 | switch (id) { |
45e898b7 | 65 | |
ad53fa10 WL |
66 | case LOCKEVENT_pv_latency_kick: |
67 | case LOCKEVENT_pv_hash_hops: | |
68 | kicks += per_cpu(EVENT_COUNT(pv_kick_unlock), cpu); | |
45e898b7 WL |
69 | break; |
70 | ||
ad53fa10 WL |
71 | case LOCKEVENT_pv_latency_wake: |
72 | kicks += per_cpu(EVENT_COUNT(pv_kick_wake), cpu); | |
45e898b7 WL |
73 | break; |
74 | } | |
75 | } | |
76 | ||
ad53fa10 | 77 | if (id == LOCKEVENT_pv_hash_hops) { |
66876595 | 78 | u64 frac = 0; |
45e898b7 | 79 | |
66876595 | 80 | if (kicks) { |
ad53fa10 | 81 | frac = 100ULL * do_div(sum, kicks); |
66876595 DB |
82 | frac = DIV_ROUND_CLOSEST_ULL(frac, kicks); |
83 | } | |
45e898b7 WL |
84 | |
85 | /* | |
86 | * Return a X.XX decimal number | |
87 | */ | |
ad53fa10 WL |
88 | len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n", |
89 | sum, frac); | |
45e898b7 WL |
90 | } else { |
91 | /* | |
92 | * Round to the nearest ns | |
93 | */ | |
ad53fa10 WL |
94 | if ((id == LOCKEVENT_pv_latency_kick) || |
95 | (id == LOCKEVENT_pv_latency_wake)) { | |
45e898b7 | 96 | if (kicks) |
ad53fa10 | 97 | sum = DIV_ROUND_CLOSEST_ULL(sum, kicks); |
45e898b7 | 98 | } |
ad53fa10 | 99 | len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum); |
45e898b7 WL |
100 | } |
101 | ||
102 | return simple_read_from_buffer(user_buf, count, ppos, buf, len); | |
103 | } | |
104 | ||
45e898b7 WL |
105 | /* |
106 | * PV hash hop count | |
107 | */ | |
ad53fa10 | 108 | static inline void lockevent_pv_hop(int hopcnt) |
45e898b7 | 109 | { |
ad53fa10 | 110 | this_cpu_add(EVENT_COUNT(pv_hash_hops), hopcnt); |
45e898b7 WL |
111 | } |
112 | ||
113 | /* | |
114 | * Replacement function for pv_kick() | |
115 | */ | |
116 | static inline void __pv_kick(int cpu) | |
117 | { | |
118 | u64 start = sched_clock(); | |
119 | ||
120 | per_cpu(pv_kick_time, cpu) = start; | |
121 | pv_kick(cpu); | |
ad53fa10 | 122 | this_cpu_add(EVENT_COUNT(pv_latency_kick), sched_clock() - start); |
45e898b7 WL |
123 | } |
124 | ||
125 | /* | |
126 | * Replacement function for pv_wait() | |
127 | */ | |
128 | static inline void __pv_wait(u8 *ptr, u8 val) | |
129 | { | |
130 | u64 *pkick_time = this_cpu_ptr(&pv_kick_time); | |
131 | ||
132 | *pkick_time = 0; | |
133 | pv_wait(ptr, val); | |
134 | if (*pkick_time) { | |
ad53fa10 | 135 | this_cpu_add(EVENT_COUNT(pv_latency_wake), |
45e898b7 | 136 | sched_clock() - *pkick_time); |
ad53fa10 | 137 | lockevent_inc(pv_kick_wake); |
45e898b7 WL |
138 | } |
139 | } | |
140 | ||
141 | #define pv_kick(c) __pv_kick(c) | |
142 | #define pv_wait(p, v) __pv_wait(p, v) | |
143 | ||
fb346fd9 WL |
144 | #endif /* CONFIG_PARAVIRT_SPINLOCKS */ |
145 | ||
146 | #else /* CONFIG_LOCK_EVENT_COUNTS */ | |
45e898b7 | 147 | |
ad53fa10 | 148 | static inline void lockevent_pv_hop(int hopcnt) { } |
45e898b7 | 149 | |
fb346fd9 | 150 | #endif /* CONFIG_LOCK_EVENT_COUNTS */ |