Date: Thu, 12 Jan 2006 22:45:13 -0800 (PST) From: kamal kc <kamal_ckk@yahoo.com> To: freebsd <freebsd-hackers@freebsd.org> Subject: Re: rescheduling tasks using swi_add() Message-ID: <20060113064513.73470.qmail@web30006.mail.mud.yahoo.com> In-Reply-To: <200601121410.53884.jhb@freebsd.org>
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--- John Baldwin <jhb@freebsd.org> wrote:
> On Thursday 12 January 2006 06:19 am, kamal kc
> wrote:
> > --- kamal kc <kamal_ckk@yahoo.com> wrote:
> > > > Queue a task to a taskqueue. Behind the
> scenes
> > >
> > > that
> > >
> > > > will invoke a swi_add if
> > > > you use the taskqueue_swi queue. However,
> given
> > > > that you want to do some
> > > > rather complicated work, you'd be better off
> > > > creating a dedicated taskqueue
> > > > thread and queueing tasks off to it I think.
> > >
> > > thanks for the suggestion on the taskqueue. i
> tried
> > > it
> > >
> > > on my dummy kernel module and got some output
> but i
> > > am not sure if i followed the correct steps to
> > > use the taskqueue. the only thing i found
> > > was the man pages and the taskqueue.h.
> > >
> > > here is the code:
> > > -----------------------
> > >
> > > struct taskqueue_arguments
> > > { int a;
> > > int b;
> > > };
> > >
> > > void taskqueue_function(void *,int);
> > > typedef void taskqueue_function_t(void *,int);
> > >
> > > /* taskqueue function */
> > > void taskqueue_function(void *arguments,int
> int_arg)
> > > {
> > > struct taskqueue_arguments *arg;
> > > arg=(struct taskqueue_arguments *)arguments;
> > > printf("\ntakqueue_function was called the
> args
> > > are %d %d",arg->a,arg->b);
> > > return;
> > > }
> > >
> > > /* function implementing the syscall */
> > > static int
> > > hello(struct thread *td, void *arg)
> > > { .........
> > > struct task mytask;
> > > taskqueue_function_t
> *taskqueue_function_ptr;
> > > taskqueue_function_ptr=taskqueue_function;
> > >
> > > struct taskqueue_arguments arg_var;
> > > arg_var.a=10;
> > > arg_var.b=20;
> >
> >
>
TASK_INIT(&mytask,50,taskqueue_function_ptr,&arg_var);
> >
> > > taskqueue_enqueue(taskqueue_swi, &mytask);
>
> You can just use the name of the function w/o having
> to have an explicit
> function pointer var:
>
> TASK_INIT(&mytask, 50, taskqueue_functino,
> &arg_var);
>
> > >
> > > ...........
> > > }
> >
> > dear all ,
> >
> > i run the above code and the kernel
> > would crash whenever i would do the syscall for
> few
> > number of times. the crashing process is
> > (swi6: task queue). the kernel crashes very soon
> > when i make the system call in a loop.
> >
> > i guess i didn't follow all the steps to use
> > the taskqueue ....
> >
> > i think some of you can help what did i
> > miss ....
the problem is solved i guess.
now i used the structure :
struct taskqueue_struct
{ struct task mytask;
int a;
int b;
}
everytime i call TASK_INIT() i allocate memory for
the taskqueue_struct.
and in the handler function deallocate the struct
taskqueue_struct.
this allowed me to do memory safe operation i guess
!!
>
> Are you calling TASK_INIT() while your task is still
> pending? Just init the
> task the first time, then call enqueue() to queue it
> up. You might want to
> call TASK_INIT() during the MOD_LOAD() event in your
> module handler for
> example. Be sure to call taskqueue_drain() during
> MOD_UNLOAD() to make sure
> your task has finished all the pending executes
> before your module is
> unloaded as well.
yes , i will do these things. now i will try to make a
separate
taskqueue thread for the job like you said before. i
am
looking at the kthread and other stuffs. i am more
optimistic
now than ever..
i am enjoying these stuffs ..
thanks,
kamal
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