> could you please try the following hunk?
>
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 6808cd9526c67..63c6960262861 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -648,7 +648,8 @@ alternative_if ARM64_HAS_IRQ_PRIO_MASKING
> orr x24, x24, x0
> alternative_else_nop_endif
>
> - cbnz x24, 2f // preempt count != 0
> + 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
>
After correctly applying this patch I do not see large latencies, >15M
iterations and counting.
# ./cyclictest -S -m -n -p 99 -i 200 -h 700 -f
# /dev/cpu_dma_latency set to 0us
policy: fifo: loadavg: 0.04 0.06 0.18 1/134 2043
T: 0 ( 1968) P:99 I:200 C:15081932 Min: 6 Act: 8 Avg: 7 Max: 22
T: 1 ( 1969) P:99 I:200 C:15081831 Min: 6 Act: 9 Avg: 7 Max: 17
T: 2 ( 1970) P:99 I:200 C:15081727 Min: 6 Act: 9 Avg: 8 Max: 17
T: 3 ( 1971) P:99 I:200 C:15081619 Min: 6 Act: 9 Avg: 8 Max: 18
I apologize for messing this up the first time. I had copied the text
strait from gmail and it failed to apply. If I had used 'patch -l' or
copied it from the archive, then it directly applies and I wouldn't
have messed up when I put it in manually. Just for reference here's
how I screwed it up:
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 6808cd9526c6..be0933a3f5e3 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -651,7 +651,8 @@ alternative_else_nop_endif
cbnz x24, 2f // preempt count != 0
ldr w24, [tsk, #TSK_TI_PREEMPT_LAZY] // get preempt
lazy count
- cbnz w24, 2f // preempt
lazy count != 0
+ cbz x24, 1f //
(need_resched + count) == 0
+ cbnz w24, 2f // count != 0
ldr x0, [tsk, #TSK_TI_FLAGS] // get flags
tbz x0, #TIF_NEED_RESCHED_LAZY, 2f // needs rescheduling?
thanks,
Paul
