Re: poor cyclictest results with 5.0 series rt for arm64

[Paul Thomas <pthomas8589@gmail.com>]

> so it seems to works but I *think* that at 610.156813 shouldn't be there
> and it should switch to cyclictest. But if it is the broken irq-exit
> path then this should fix it:
>
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 63c6960262861..27a16c2711981 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -649,13 +649,7 @@ alternative_if ARM64_HAS_IRQ_PRIO_MASKING
>  alternative_else_nop_endif
>
>         cbz     x24, 1f                                 // (need_resched + count) == 0
> -       cbnz    w24, 2f                                 // count != 0
> -
> -       ldr     w24, [tsk, #TSK_TI_PREEMPT_LAZY]        // get preempt lazy count
> -       cbnz    w24, 2f                                 // preempt lazy count != 0
> -
> -       ldr     x0, [tsk, #TSK_TI_FLAGS]                // get flags
> -       tbz     x0, #TIF_NEED_RESCHED_LAZY, 2f          // needs rescheduling?
> +       b       2f                                      // count != 0
>  1:
>         bl      preempt_schedule_irq            // irq en/disable is done inside
>  2:
This doesn't look like it's against 5.2.y-rt or 5.0.y-rt? I don't see
a (need_resched + count) == 0 line?

-Paul