faster way to find task

faster way to find task

[loody]

Dear all:
Is there faster way to find a give name of task?
for example, I have a thread, named "test", is there faster way to get the
task struct  by passing "test" to some kernel api?


-- 
Regards,
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faster way to find task

[loody]

Hi all:

2011/7/12 loody <miloody@gmail.com>

> Dear all:
> Is there faster way to find a give name of task?
> for example, I have a thread, named "test", is there faster way to get the
> task struct  by passing "test" to some kernel api?
>
>
> --
> Regards,
>
I found a way as below:
for_each_process(task) {
printk(?%s[%d]\n?, task->comm, task->pid);
}

But it is time-consuming to do so if I periodically want to know whether
"test" exist or not.
is there better way to do so?


-- 
Regards,
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faster way to find task

[Nuno Martins]

On Mon, Jul 11, 2011 at 5:34 PM, loody <miloody@gmail.com> wrote:

> Hi all:
>
>
> 2011/7/12 loody <miloody@gmail.com>
>
>> Dear all:
>> Is there faster way to find a give name of task?
>> for example, I have a thread, named "test", is there faster way to get the
>> task struct  by passing "test" to some kernel api?
>>
>>
>> --
>> Regards,
>>
> I found a way as below:
> for_each_process(task) {
> printk(?%s[%d]\n?, task->comm, task->pid);
> }
>
> But it is time-consuming to do so if I periodically want to know whether
> "test" exist or not.
> is there better way to do so?
>
>
>
If you have the thread pid you could find it really fast. By name i don't
know any function that could help you with that.
You could search [1,2] for functions that could help you with that.
If you are invoking from the thread you want, inside the kernel you can get
the current variable that points to ther current process.


 [1]  http://lxr.linux.no/linux+v2.6.39/kernel/pid.c#L426
 [2] struct task_struct<http://lxr.linux.no/linux+v2.6.39/+code=task_struct>*
find_task_by_vpid<http://lxr.linux.no/linux+v2.6.39/+code=find_task_by_vpid>
(pid_t <http://lxr.linux.no/linux+v2.6.39/+code=pid_t>
vnr<http://lxr.linux.no/linux+v2.6.39/+code=vnr>
);

Have a good work.


> --
> Regards,
>
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> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
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>
>


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faster way to find task

[loody]

hi:


2011/7/12 Nuno Martins <nuno.m.g.martins@gmail.com>:
>
>
> On Mon, Jul 11, 2011 at 5:34 PM, loody <miloody@gmail.com> wrote:
>>
>> Hi all:
>>
>> 2011/7/12 loody <miloody@gmail.com>
>>>
>>> Dear all:
>>> Is there faster way to find a give name of task?
>>> for example, I have a thread, named "test", is there faster way to get
>>> the task struct ?by passing "test" to some kernel api?
>>>
>>> --
>>> Regards,
>>
>> I found a way as below:
>> for_each_process(task) {
>> printk(?%s[%d]\n?, task->comm, task->pid);
>> }
>>
>> But it is time-consuming to do so if I periodically want to know whether
>> "test" exist or not.
>> is there better way to do so?
>>
Thanks for your help :)
> If you have the thread pid you could find it really fast. By name i don't
> know any function that could help you with that.

actually, I only have the name for searching, since the thread start
and finish periodically, pid of it will change dynamically. The only
thing that fixed is the name of the thread.

> You could search [1,2] for functions that could help you with that.
> If you are invoking from the thread you want, inside the kernel you can get
> the current variable that points to ther current process.
>
> ?[1] ?http://lxr.linux.no/linux+v2.6.39/kernel/pid.c#L426
> ?[2]?struct task_struct *find_task_by_vpid(pid_t vnr);
> Have a good work.
I will check what you mentioned above.
Thanks a lot,