1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Test for find_*_bit functions.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (c) 2017 Cavium.
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun /*
9*4882a593Smuzhiyun * find_bit functions are widely used in kernel, so the successful boot
10*4882a593Smuzhiyun * is good enough test for correctness.
11*4882a593Smuzhiyun *
12*4882a593Smuzhiyun * This test is focused on performance of traversing bitmaps. Two typical
13*4882a593Smuzhiyun * scenarios are reproduced:
14*4882a593Smuzhiyun * - randomly filled bitmap with approximately equal number of set and
15*4882a593Smuzhiyun * cleared bits;
16*4882a593Smuzhiyun * - sparse bitmap with few set bits at random positions.
17*4882a593Smuzhiyun */
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun #include <linux/bitops.h>
20*4882a593Smuzhiyun #include <linux/kernel.h>
21*4882a593Smuzhiyun #include <linux/list.h>
22*4882a593Smuzhiyun #include <linux/module.h>
23*4882a593Smuzhiyun #include <linux/printk.h>
24*4882a593Smuzhiyun #include <linux/random.h>
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun #define BITMAP_LEN (4096UL * 8 * 10)
27*4882a593Smuzhiyun #define SPARSE 500
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun static DECLARE_BITMAP(bitmap, BITMAP_LEN) __initdata;
30*4882a593Smuzhiyun static DECLARE_BITMAP(bitmap2, BITMAP_LEN) __initdata;
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun /*
33*4882a593Smuzhiyun * This is Schlemiel the Painter's algorithm. It should be called after
34*4882a593Smuzhiyun * all other tests for the same bitmap because it sets all bits of bitmap to 1.
35*4882a593Smuzhiyun */
test_find_first_bit(void * bitmap,unsigned long len)36*4882a593Smuzhiyun static int __init test_find_first_bit(void *bitmap, unsigned long len)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun unsigned long i, cnt;
39*4882a593Smuzhiyun ktime_t time;
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun time = ktime_get();
42*4882a593Smuzhiyun for (cnt = i = 0; i < len; cnt++) {
43*4882a593Smuzhiyun i = find_first_bit(bitmap, len);
44*4882a593Smuzhiyun __clear_bit(i, bitmap);
45*4882a593Smuzhiyun }
46*4882a593Smuzhiyun time = ktime_get() - time;
47*4882a593Smuzhiyun pr_err("find_first_bit: %18llu ns, %6ld iterations\n", time, cnt);
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun return 0;
50*4882a593Smuzhiyun }
51*4882a593Smuzhiyun
test_find_next_bit(const void * bitmap,unsigned long len)52*4882a593Smuzhiyun static int __init test_find_next_bit(const void *bitmap, unsigned long len)
53*4882a593Smuzhiyun {
54*4882a593Smuzhiyun unsigned long i, cnt;
55*4882a593Smuzhiyun ktime_t time;
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun time = ktime_get();
58*4882a593Smuzhiyun for (cnt = i = 0; i < BITMAP_LEN; cnt++)
59*4882a593Smuzhiyun i = find_next_bit(bitmap, BITMAP_LEN, i) + 1;
60*4882a593Smuzhiyun time = ktime_get() - time;
61*4882a593Smuzhiyun pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt);
62*4882a593Smuzhiyun
63*4882a593Smuzhiyun return 0;
64*4882a593Smuzhiyun }
65*4882a593Smuzhiyun
test_find_next_zero_bit(const void * bitmap,unsigned long len)66*4882a593Smuzhiyun static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len)
67*4882a593Smuzhiyun {
68*4882a593Smuzhiyun unsigned long i, cnt;
69*4882a593Smuzhiyun ktime_t time;
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun time = ktime_get();
72*4882a593Smuzhiyun for (cnt = i = 0; i < BITMAP_LEN; cnt++)
73*4882a593Smuzhiyun i = find_next_zero_bit(bitmap, len, i) + 1;
74*4882a593Smuzhiyun time = ktime_get() - time;
75*4882a593Smuzhiyun pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);
76*4882a593Smuzhiyun
77*4882a593Smuzhiyun return 0;
78*4882a593Smuzhiyun }
79*4882a593Smuzhiyun
test_find_last_bit(const void * bitmap,unsigned long len)80*4882a593Smuzhiyun static int __init test_find_last_bit(const void *bitmap, unsigned long len)
81*4882a593Smuzhiyun {
82*4882a593Smuzhiyun unsigned long l, cnt = 0;
83*4882a593Smuzhiyun ktime_t time;
84*4882a593Smuzhiyun
85*4882a593Smuzhiyun time = ktime_get();
86*4882a593Smuzhiyun do {
87*4882a593Smuzhiyun cnt++;
88*4882a593Smuzhiyun l = find_last_bit(bitmap, len);
89*4882a593Smuzhiyun if (l >= len)
90*4882a593Smuzhiyun break;
91*4882a593Smuzhiyun len = l;
92*4882a593Smuzhiyun } while (len);
93*4882a593Smuzhiyun time = ktime_get() - time;
94*4882a593Smuzhiyun pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt);
95*4882a593Smuzhiyun
96*4882a593Smuzhiyun return 0;
97*4882a593Smuzhiyun }
98*4882a593Smuzhiyun
test_find_next_and_bit(const void * bitmap,const void * bitmap2,unsigned long len)99*4882a593Smuzhiyun static int __init test_find_next_and_bit(const void *bitmap,
100*4882a593Smuzhiyun const void *bitmap2, unsigned long len)
101*4882a593Smuzhiyun {
102*4882a593Smuzhiyun unsigned long i, cnt;
103*4882a593Smuzhiyun ktime_t time;
104*4882a593Smuzhiyun
105*4882a593Smuzhiyun time = ktime_get();
106*4882a593Smuzhiyun for (cnt = i = 0; i < BITMAP_LEN; cnt++)
107*4882a593Smuzhiyun i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1);
108*4882a593Smuzhiyun time = ktime_get() - time;
109*4882a593Smuzhiyun pr_err("find_next_and_bit: %18llu ns, %6ld iterations\n", time, cnt);
110*4882a593Smuzhiyun
111*4882a593Smuzhiyun return 0;
112*4882a593Smuzhiyun }
113*4882a593Smuzhiyun
find_bit_test(void)114*4882a593Smuzhiyun static int __init find_bit_test(void)
115*4882a593Smuzhiyun {
116*4882a593Smuzhiyun unsigned long nbits = BITMAP_LEN / SPARSE;
117*4882a593Smuzhiyun
118*4882a593Smuzhiyun pr_err("\nStart testing find_bit() with random-filled bitmap\n");
119*4882a593Smuzhiyun
120*4882a593Smuzhiyun get_random_bytes(bitmap, sizeof(bitmap));
121*4882a593Smuzhiyun get_random_bytes(bitmap2, sizeof(bitmap2));
122*4882a593Smuzhiyun
123*4882a593Smuzhiyun test_find_next_bit(bitmap, BITMAP_LEN);
124*4882a593Smuzhiyun test_find_next_zero_bit(bitmap, BITMAP_LEN);
125*4882a593Smuzhiyun test_find_last_bit(bitmap, BITMAP_LEN);
126*4882a593Smuzhiyun
127*4882a593Smuzhiyun /*
128*4882a593Smuzhiyun * test_find_first_bit() may take some time, so
129*4882a593Smuzhiyun * traverse only part of bitmap to avoid soft lockup.
130*4882a593Smuzhiyun */
131*4882a593Smuzhiyun test_find_first_bit(bitmap, BITMAP_LEN / 10);
132*4882a593Smuzhiyun test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
133*4882a593Smuzhiyun
134*4882a593Smuzhiyun pr_err("\nStart testing find_bit() with sparse bitmap\n");
135*4882a593Smuzhiyun
136*4882a593Smuzhiyun bitmap_zero(bitmap, BITMAP_LEN);
137*4882a593Smuzhiyun bitmap_zero(bitmap2, BITMAP_LEN);
138*4882a593Smuzhiyun
139*4882a593Smuzhiyun while (nbits--) {
140*4882a593Smuzhiyun __set_bit(prandom_u32() % BITMAP_LEN, bitmap);
141*4882a593Smuzhiyun __set_bit(prandom_u32() % BITMAP_LEN, bitmap2);
142*4882a593Smuzhiyun }
143*4882a593Smuzhiyun
144*4882a593Smuzhiyun test_find_next_bit(bitmap, BITMAP_LEN);
145*4882a593Smuzhiyun test_find_next_zero_bit(bitmap, BITMAP_LEN);
146*4882a593Smuzhiyun test_find_last_bit(bitmap, BITMAP_LEN);
147*4882a593Smuzhiyun test_find_first_bit(bitmap, BITMAP_LEN);
148*4882a593Smuzhiyun test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
149*4882a593Smuzhiyun
150*4882a593Smuzhiyun /*
151*4882a593Smuzhiyun * Everything is OK. Return error just to let user run benchmark
152*4882a593Smuzhiyun * again without annoying rmmod.
153*4882a593Smuzhiyun */
154*4882a593Smuzhiyun return -EINVAL;
155*4882a593Smuzhiyun }
156*4882a593Smuzhiyun module_init(find_bit_test);
157*4882a593Smuzhiyun
158*4882a593Smuzhiyun MODULE_LICENSE("GPL");
159