5 #include <linux/module.h>
6 #include <linux/proc_fs.h>
7 #include <linux/sched.h>
8 #include <linux/timex.h>
9 #include <linux/fair-rwlock.h>
10 #include <linux/kthread.h>
11 #include <linux/delay.h>
12 #include <linux/hardirq.h>
13 #include <linux/module.h>
14 #include <linux/percpu.h>
15 #include <asm/ptrace.h>
17 #if (NR_CPUS > 64 && (BITS_PER_LONG == 32 || NR_CPUS > 32768))
18 #error "fair rwlock needs more bits per long to deal with that many CPUs"
21 /* Test duration, in seconds */
22 #define TEST_DURATION 600
24 #define THREAD_ROFFSET 1UL
25 #define THREAD_RMASK ((NR_CPUS - 1) * THREAD_ROFFSET)
26 #define SOFTIRQ_ROFFSET (THREAD_RMASK + 1)
27 #define SOFTIRQ_RMASK ((NR_CPUS - 1) * SOFTIRQ_ROFFSET)
28 #define HARDIRQ_ROFFSET ((SOFTIRQ_RMASK | THREAD_RMASK) + 1)
29 #define HARDIRQ_RMASK ((NR_CPUS - 1) * HARDIRQ_ROFFSET)
31 #define SUBSCRIBERS_WOFFSET \
32 ((HARDIRQ_RMASK | SOFTIRQ_RMASK | THREAD_RMASK) + 1)
33 #define SUBSCRIBERS_WMASK \
34 ((NR_CPUS - 1) * SUBSCRIBERS_WOFFSET)
35 #define WRITER_MUTEX \
36 ((SUBSCRIBERS_WMASK | HARDIRQ_RMASK | SOFTIRQ_RMASK | THREAD_RMASK) + 1)
37 #define SOFTIRQ_WMASK (WRITER_MUTEX << 1)
38 #define SOFTIRQ_WOFFSET SOFTIRQ_WMASK
39 #define HARDIRQ_WMASK (SOFTIRQ_WMASK << 1)
40 #define HARDIRQ_WOFFSET HARDIRQ_WMASK
45 #define NR_INTERRUPT_READERS 2
47 /* Writer iteration delay, in ms. 0 for busy loop. */
48 #define WRITER_DELAY 1
50 static int var
[NR_VARS
];
51 static struct task_struct
*reader_threads
[NR_READERS
];
52 static struct task_struct
*writer_threads
[NR_WRITERS
];
53 static struct task_struct
*interrupt_reader
;
55 static struct fair_rwlock frwlock
= {
56 .value
= ATOMIC_LONG_INIT(0),
59 struct proc_dir_entry
*pentry
= NULL
;
61 static int reader_thread(void *data
)
65 unsigned long iter
= 0;
66 cycles_t time1
, time2
, delaymax
= 0;
68 printk("reader_thread/%lu runnning\n", (unsigned long)data
);
71 preempt_disable(); /* for get_cycles accuracy */
73 fair_read_lock(&frwlock
);
75 delaymax
= max(delaymax
, time2
- time1
);
77 for (i
= 1; i
< NR_VARS
; i
++) {
81 "Unequal cur %d/prev %d at i %d, iter %lu "
82 "in thread\n", cur
, prev
, i
, iter
);
84 fair_read_unlock(&frwlock
);
85 preempt_enable(); /* for get_cycles accuracy */
87 } while (!kthread_should_stop());
88 printk("reader_thread/%lu iterations : %lu, "
89 "max contention %llu cycles\n",
90 (unsigned long)data
, iter
, delaymax
);
94 DEFINE_PER_CPU(cycles_t
, int_delaymax
);
96 static void interrupt_reader_ipi(void *data
)
100 cycles_t time1
, time2
;
104 * Skip the ipi caller, not in irq context.
109 delaymax
= &per_cpu(int_delaymax
, smp_processor_id());
110 time1
= get_cycles();
111 fair_read_lock(&frwlock
);
112 time2
= get_cycles();
113 *delaymax
= max(*delaymax
, time2
- time1
);
115 for (i
= 1; i
< NR_VARS
; i
++) {
119 "Unequal cur %d/prev %d at i %d in interrupt\n",
122 fair_read_unlock(&frwlock
);
125 static int interrupt_reader_thread(void *data
)
127 unsigned long iter
= 0;
132 on_each_cpu(interrupt_reader_ipi
, NULL
, 0);
134 } while (!kthread_should_stop());
135 printk("interrupt_reader_thread/%lu iterations : %lu\n",
136 (unsigned long)data
, iter
);
137 for_each_online_cpu(i
) {
138 printk("interrupt readers on CPU %i, "
139 "max contention : %llu cycles\n",
140 i
, per_cpu(int_delaymax
, i
));
145 static int writer_thread(void *data
)
149 unsigned long iter
= 0;
150 cycles_t time1
, time2
, delaymax
= 0;
152 printk("writer_thread/%lu runnning\n", (unsigned long)data
);
155 preempt_disable(); /* for get_cycles accuracy */
156 time1
= get_cycles();
157 fair_write_lock_irq(&frwlock
);
158 //fair_write_lock(&frwlock);
159 time2
= get_cycles();
160 delaymax
= max(delaymax
, time2
- time1
);
161 new = (int)get_cycles();
162 for (i
= 0; i
< NR_VARS
; i
++) {
165 //fair_write_unlock(&frwlock);
166 fair_write_unlock_irq(&frwlock
);
167 preempt_enable(); /* for get_cycles accuracy */
168 if (WRITER_DELAY
> 0)
169 msleep(WRITER_DELAY
);
170 } while (!kthread_should_stop());
171 printk("writer_thread/%lu iterations : %lu, "
172 "max contention %llu cycles\n",
173 (unsigned long)data
, iter
, delaymax
);
177 static void fair_rwlock_create(void)
181 for (i
= 0; i
< NR_READERS
; i
++) {
182 printk("starting reader thread %lu\n", i
);
183 reader_threads
[i
] = kthread_run(reader_thread
, (void *)i
,
185 BUG_ON(!reader_threads
[i
]);
188 printk("starting interrupt reader %lu\n", i
);
189 interrupt_reader
= kthread_run(interrupt_reader_thread
, NULL
,
190 "frwlock_interrupt_reader");
192 for (i
= 0; i
< NR_WRITERS
; i
++) {
193 printk("starting writer thread %lu\n", i
);
194 writer_threads
[i
] = kthread_run(writer_thread
, (void *)i
,
196 BUG_ON(!writer_threads
[i
]);
200 static void fair_rwlock_stop(void)
204 for (i
= 0; i
< NR_WRITERS
; i
++) {
205 kthread_stop(writer_threads
[i
]);
208 for (i
= 0; i
< NR_READERS
; i
++) {
209 kthread_stop(reader_threads
[i
]);
212 kthread_stop(interrupt_reader
);
216 static void perform_test(const char *name
, void (*callback
)(void))
218 printk("%s\n", name
);
222 static int my_open(struct inode
*inode
, struct file
*file
)
224 perform_test("fair-rwlock-create", fair_rwlock_create
);
226 perform_test("fair-rwlock-stop", fair_rwlock_stop
);
232 static struct file_operations my_operations
= {
236 int init_module(void)
238 pentry
= create_proc_entry("testfrwlock", 0444, NULL
);
240 pentry
->proc_fops
= &my_operations
;
242 printk("NR_CPUS : %d\n", NR_CPUS
);
243 printk("THREAD_ROFFSET : %lX\n", THREAD_ROFFSET
);
244 printk("THREAD_RMASK : %lX\n", THREAD_RMASK
);
245 printk("SOFTIRQ_ROFFSET : %lX\n", SOFTIRQ_ROFFSET
);
246 printk("SOFTIRQ_RMASK : %lX\n", SOFTIRQ_RMASK
);
247 printk("HARDIRQ_ROFFSET : %lX\n", HARDIRQ_ROFFSET
);
248 printk("HARDIRQ_RMASK : %lX\n", HARDIRQ_RMASK
);
249 printk("SUBSCRIBERS_WOFFSET : %lX\n", SUBSCRIBERS_WOFFSET
);
250 printk("SUBSCRIBERS_WMASK : %lX\n", SUBSCRIBERS_WMASK
);
251 printk("WRITER_MUTEX : %lX\n", WRITER_MUTEX
);
252 printk("SOFTIRQ_WMASK : %lX\n", SOFTIRQ_WMASK
);
253 printk("HARDIRQ_WMASK : %lX\n", HARDIRQ_WMASK
);
258 void cleanup_module(void)
260 remove_proc_entry("testfrwlock", NULL
);
263 MODULE_LICENSE("GPL");
264 MODULE_AUTHOR("Mathieu Desnoyers");
265 MODULE_DESCRIPTION("Fair rwlock test");