Re: [PATCH 18/23] sched,locktorture: Convert to sched_set_fifo()
From: Paul E. McKenney
Date: Wed Apr 22 2020 - 11:51:37 EST
On Wed, Apr 22, 2020 at 01:27:37PM +0200, Peter Zijlstra 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 prio from 99 to 50.
>
> Cc: paulmck@xxxxxxxxxx
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> ---
> kernel/locking/locktorture.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> --- a/kernel/locking/locktorture.c
> +++ b/kernel/locking/locktorture.c
> @@ -436,8 +436,6 @@ static int torture_rtmutex_lock(void) __
>
> static void torture_rtmutex_boost(struct torture_random_state *trsp)
> {
> - int policy;
> - struct sched_param param;
> const unsigned int factor = 50000; /* yes, quite arbitrary */
>
> if (!rt_task(current)) {
> @@ -448,8 +446,7 @@ static void torture_rtmutex_boost(struct
> */
> if (trsp && !(torture_random(trsp) %
> (cxt.nrealwriters_stress * factor))) {
> - policy = SCHED_FIFO;
> - param.sched_priority = MAX_RT_PRIO - 1;
> + sched_set_fifo(current);
> } else /* common case, do nothing */
> return;
> } else {
> @@ -462,13 +459,10 @@ static void torture_rtmutex_boost(struct
> */
> if (!trsp || !(torture_random(trsp) %
> (cxt.nrealwriters_stress * factor * 2))) {
> - policy = SCHED_NORMAL;
> - param.sched_priority = 0;
> + sched_set_normal(current, 0);
> } else /* common case, do nothing */
> return;
> }
> -
> - sched_setscheduler_nocheck(current, policy, ¶m);
> }
>
> static void torture_rtmutex_delay(struct torture_random_state *trsp)
>
>