【Linux设备驱动程序（第三版）】----定时器：Timer

【Linux设备驱动程序（第三版）】----定时器：Timer

jit.c

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/timer.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <asm/hardirq.h>
#include <linux/sched.h>//jiffies
#include <linux/kernel.h>
#include <linux/types.h>//u64
#include <linux/fs.h>//file_operations, file
#include <linux/completion.h>
#include <asm/uaccess.h>//copy_to_user & copy_from_user

int delay = HZ;

enum jit_files {
JIT_BUSY,
JIT_SCHED,
JIT_QUEUE,
JIT_SCHEDTO
};

int tdelay = 10;

struct jit_data {
struct timer_list timer;
struct tasklet_struct tlet;
int hi;
wait_queue_head_t wait;
unsigned long prevjiffies;
unsigned char *buf;
int loops;
};

int jit_fn(char *buf, char **start, off_t offset, int len, int *eof, void *data)
{
unsigned long j0, j1;
wait_queue_head_t wait;

init_waitqueue_head(&wait);
j0 = jiffies;
j1 = j0 + delay;

switch((long)data){
case JIT_BUSY:
while(time_before(jiffies, j1))
cpu_relax();
break;
case JIT_SCHED:
while(time_before(jiffies, j1))
schedule();
break;
case JIT_QUEUE:
wait_event_interruptible_timeout(wait, 0, delay);
break;
case JIT_SCHEDTO:
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(delay);
break;
}
j1 = jiffies;
len = sprintf(buf, "%9li %9li\n", j0, j1);
*start = buf;
return len;
}

int jit_currentime(char *buf, char **start, off_t offset, int len, int *eof, void *data)
{
struct timeval tv1;
struct timespec tv2;
unsigned long j1;
u64 j2;

j1 = jiffies;
j2 = get_jiffies_64();
do_gettimeofday(&tv1);
tv2 = current_kernel_time();

len = 0;
len += sprintf(buf,"0x%08lx 0x%016Lx %10i.%06i\n"
"%40i.%09i\n",
j1, j2,
(int) tv1.tv_sec, (int) tv1.tv_usec,
(int) tv2.tv_sec, (int) tv2.tv_nsec);
*start = buf;
return len;
}

#define JIT_ASYNC_LOOPS 5

void jit_timer_fn(unsigned long arg)
{
struct jit_data *data = (struct jit_data *)arg;
unsigned long j = jiffies;
data->buf += sprintf(data->buf,"%9li	%3li	%i	%6i	%i	%s\n",j,j-data->prevjiffies,in_interrupt()?1:0,
current->pid, smp_processor_id(), current->comm);
if(--data->loops){
data->timer.expires += tdelay;
data->prevjiffies = j;
add_timer(&data->timer);
}else{
wake_up_interruptible(&data->wait);
}
}

int jit_timer(char *buf, char **start, off_t offset, int len, int *eof, void *unused_data)
{
struct jit_data *data;
char *buf2 = buf;
unsigned long j = jiffies;

data = kmalloc(sizeof(*data), GFP_KERNEL);
if(!data)
return -ENOMEM;

init_timer(&data->timer);
init_waitqueue_head(&data->wait);

buf2 += sprintf(buf2,"	time	delta	inirq	pid	cpu	command\n");
buf2 += sprintf(buf2,"%9li	%3li	%i	%6i	%i	%s\n",j,0L,in_interrupt()?1:0,
current->pid, smp_processor_id(), current->comm);

data->prevjiffies = j;
data->buf = buf2;
data->loops = JIT_ASYNC_LOOPS;

data->timer.data = (unsigned long)data;
data->timer.function = jit_timer_fn;
data->timer.expires = j + tdelay;
add_timer(&data->timer);

wait_event_interruptible(data->wait, !data->loops);
if(signal_pending(current))
return -ERESTARTSYS;
buf2 = data->buf;
kfree(data);
*eof =1;
return buf2 - buf;
}

int __init jit_init(void)
{
create_proc_read_entry("jit_currentime", 0, NULL, jit_currentime, NULL);
create_proc_read_entry("jitbusy", 0, NULL, jit_fn, (void *)JIT_BUSY);
create_proc_read_entry("jitsched", 0, NULL, jit_fn, (void *)JIT_SCHED);
create_proc_read_entry("jitqueue", 0, NULL, jit_fn, (void *)JIT_QUEUE);
create_proc_read_entry("jitschedto", 0, NULL, jit_fn, (void *)JIT_SCHEDTO);

create_proc_read_entry("jittimer", 0, NULL, jit_timer, NULL);
return 0;
}

void __exit jit_exit(void)
{
remove_proc_entry("jit_currentime", NULL);
remove_proc_entry("jitbusy", NULL);
remove_proc_entry("jitsched", NULL);
remove_proc_entry("jitqueue", NULL);
remove_proc_entry("jitschedto", NULL);

remove_proc_entry("jittimer", NULL);
}

MODULE_LICENSE("Dual BSD/GPL");
module_init(jit_init);
module_exit(jit_exit);

Makefile

obj-m:= jit.o
modules-objs:= jit.o

KDIR:= /usr/src/linux-headers-2.6.31-14-generic/
PWD:= $(shell pwd)

default:
make -C $(KDIR) M=$(PWD) modules
clean:
rm -rf *.ko *.mod.c *.mod.o *.o *.markers *.symvers *.order

装载

insmod jit.ko

测试

cat /proc/jittimer

cat /proc/jittimer
time	delta	inirq	  pid	cpu	command
3244715	  0	0	  7292	1	cat
3244725	 10	1	  4935	1	gnome-terminal
3244735	 10	1	     0	1	swapper
3244745	 10	1	     0	1	swapper
3244755	 10	1	     0	1	swapper
3244765	 10	1	     0	1	swapper

卸载

rmmod jit