Re: [PATCH 09/23] sched,ivtv: Convert to sched_set_fifo*()

[Steven Rostedt]

On Wed, 22 Apr 2020 13:27:28 +0200
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> Because SCHED_FIFO is a broken scheduler model (see previous patches)
> take away the priority field, the kernel can't possibly make an
> informed decision.
> 
> Effectively changes from 99 to 50.

I wonder for the 99 users, we should have a sched_set_high() that would set
the task to something like 75.

That is, above default 50?


-- Steve


> 
> Cc: hverkuil@xxxxxxxxx
> Cc: awalls@xxxxxxxxxxxxxxxx
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
> ---
>  drivers/media/pci/ivtv/ivtv-driver.c |    4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> --- a/drivers/media/pci/ivtv/ivtv-driver.c
> +++ b/drivers/media/pci/ivtv/ivtv-driver.c
> @@ -737,8 +737,6 @@ static void ivtv_process_options(struct
>   */
>  static int ivtv_init_struct1(struct ivtv *itv)
>  {
> -	struct sched_param param = { .sched_priority = 99 };
> -
>  	itv->base_addr = pci_resource_start(itv->pdev, 0);
>  	itv->enc_mbox.max_mbox = 2; /* the encoder has 3 mailboxes (0-2) */
>  	itv->dec_mbox.max_mbox = 1; /* the decoder has 2 mailboxes (0-1) */
> @@ -758,7 +756,7 @@ static int ivtv_init_struct1(struct ivtv
>  		return -1;
>  	}
>  	/* must use the FIFO scheduler as it is realtime sensitive */
> -	sched_setscheduler(itv->irq_worker_task, SCHED_FIFO, &param);
> +	sched_set_fifo(itv->irq_worker_task);
>  
>  	kthread_init_work(&itv->irq_work, ivtv_irq_work_handler);
>  
>