Hi...
Don't forget to CC to kernelnewbies too.... Our discussion will be
archieved, so someone else can learn something from this in the future.
> BTW, my kernel is linux-2.4.18 with preempt patch, and these code
> runs on an ARM board.
Hm...ARM. OK, just FYI, I know nothing about ARM, all I say previously
and now are based on x86 32 bit, so some assumptions might be wrong.
> like this:
> 532 spinlock_t my_lock = SPIN_LOCK_UNLOCKED;
> 533
> 534 void dummy_loop()
> 535 {
> 536 pid_t mypid = current->pid;
> 537 unsigned long long i;
> 538 for (i = 0; i < 1000; i++) {
> 539 spin_lock(&my_lock);
> 540 printk("thread %d, loop: %u "
> 541 ,mypid,i);
> 542 printk("jiffies: %u, time slice: %d\n"
> 543 ,jiffies,current->counter);
> 544 spin_unlock(&my_lock);
> 545 }
> 546 printk("this is thread %d, total:
> %u\n",current->pid,i);
> 547 for (;;);
> 548 }
Hm..very strange. Somehow, if we grab spin lock, pid is printed
consistently. And you said, you patch your kernel with preempt patch.
This made me suspect....could this be a bug inside that preempt patch?
> I print loop number and I expect to see it prints
>
> 139 thread 11, loop: 21 jiffies: 113, time slice: 2
> 140 thread 11, loop: 22 jiffies: 113, time slice: 2
> 141 thread 11, loop: 23 jiffies: 113, time slice: 2
> 142 thread 11, loop: 24 jiffies: 114, time slice: 1
> 143 thread 11, loop: 25 jiffies: 114, time slice: 1
> 144 thread 10, loop: 20 jiffies: 115, time slice: 6
> 145 thread 10, loop: 21 jiffies: 115, time slice: 6
> 146 thread 10, loop: 22 jiffies: 116, time slice: 5
What? "loop" goes to 25 and then goes back to 20? How come? BTW, how
many kernel thread did you make? 1? 2? More? Can you paste your entire
code please? This guessing game isn't effective at all.
regards,
Mulyadi
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