* [PATCH] drivers/clocksource/arm_arch_timer: Tighten Allwinner arch timer workaround
@ 2022-11-09 21:10 ` Ilya Dikariev
0 siblings, 0 replies; 6+ messages in thread
From: Ilya Dikariev @ 2022-11-09 21:10 UTC (permalink / raw)
To: Mark Rutland, Marc Zyngier
Cc: Daniel Lezcano, Thomas Gleixner, Samuel Holland, Chen-Yu Tsai,
Jernej Škrabec, linux-sunxi, linux-arm-kernel, linux-kernel,
linux-sunxi
As we know, the Allwinner A64 SoC has a buggy RCU time unit. The
workaround named UNKNOWN1 was not sufficient to cover some more buggy
bunches of this SoC. This workaround diminish the mask to 8 bits instead
of 9.
An example run of timer test tool https://github.com/smaeul/timer-tools
on PinePhone device (owns the A64 SoC) gives following result on a non
patched kernel (cut off):
Running parallel counter test...
0: Failed after 5507 reads (0.003578 s)
0: 0x0000000c8272cbf1 -> 0x0000000c8272ccff -> 0x0000000c8272cc0e ( 0.011 ms)
2: Failed after 14518 reads (0.009248 s)
2: 0x0000000c827513f1 -> 0x0000000c82751300 -> 0x0000000c8275140e ( -0.010 ms)
3: Failed after 14112 reads (0.008730 s)
3: 0x0000000c8274f3f2 -> 0x0000000c8274f300 -> 0x0000000c8274f40d ( -0.010 ms)
1: Failed after 12030 reads (0.008409 s)
1: 0x0000000c8274abf1 -> 0x0000000c8274acff -> 0x0000000c8274ac0f ( 0.011 ms)
1: 0x0000000c827759f2 -> 0x0000000c82775aff -> 0x0000000c82775a0e ( 0.011 ms)
0: 0x0000000c8277a9f2 -> 0x0000000c8277aaff -> 0x0000000c8277aa0d ( 0.011 ms)
2: 0x0000000c8278f3f1 -> 0x0000000c8278f300 -> 0x0000000c8278f40e ( -0.010 ms)
0: 0x0000000c82785ff2 -> 0x0000000c82784300 -> 0x0000000c8278600d ( -0.309 ms)
After the proposed patch applied the test runs
correctly (~2 hours of testing with a tool above without fails)
Signed-off-by: Ilya Dikariev <dikarill@b-tu.de>
---
drivers/clocksource/arm_arch_timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index a7ff77550e17..3019faa263f5 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -371,7 +371,7 @@ static u64 notrace arm64_858921_read_cntvct_el0(void)
do { \
_val = read_sysreg(reg); \
_retries--; \
- } while (((_val + 1) & GENMASK(8, 0)) <= 1 && _retries); \
+ } while (((_val + 1) & GENMASK(7, 0)) <= 1 && _retries); \
\
WARN_ON_ONCE(!_retries); \
_val; \
--
2.25.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH] drivers/clocksource/arm_arch_timer: Tighten Allwinner arch timer workaround
@ 2022-11-09 21:10 ` Ilya Dikariev
0 siblings, 0 replies; 6+ messages in thread
From: Ilya Dikariev @ 2022-11-09 21:10 UTC (permalink / raw)
To: Mark Rutland, Marc Zyngier
Cc: Daniel Lezcano, Thomas Gleixner, Samuel Holland, Chen-Yu Tsai,
Jernej Škrabec, linux-sunxi, linux-arm-kernel, linux-kernel,
linux-sunxi
As we know, the Allwinner A64 SoC has a buggy RCU time unit. The
workaround named UNKNOWN1 was not sufficient to cover some more buggy
bunches of this SoC. This workaround diminish the mask to 8 bits instead
of 9.
An example run of timer test tool https://github.com/smaeul/timer-tools
on PinePhone device (owns the A64 SoC) gives following result on a non
patched kernel (cut off):
Running parallel counter test...
0: Failed after 5507 reads (0.003578 s)
0: 0x0000000c8272cbf1 -> 0x0000000c8272ccff -> 0x0000000c8272cc0e ( 0.011 ms)
2: Failed after 14518 reads (0.009248 s)
2: 0x0000000c827513f1 -> 0x0000000c82751300 -> 0x0000000c8275140e ( -0.010 ms)
3: Failed after 14112 reads (0.008730 s)
3: 0x0000000c8274f3f2 -> 0x0000000c8274f300 -> 0x0000000c8274f40d ( -0.010 ms)
1: Failed after 12030 reads (0.008409 s)
1: 0x0000000c8274abf1 -> 0x0000000c8274acff -> 0x0000000c8274ac0f ( 0.011 ms)
1: 0x0000000c827759f2 -> 0x0000000c82775aff -> 0x0000000c82775a0e ( 0.011 ms)
0: 0x0000000c8277a9f2 -> 0x0000000c8277aaff -> 0x0000000c8277aa0d ( 0.011 ms)
2: 0x0000000c8278f3f1 -> 0x0000000c8278f300 -> 0x0000000c8278f40e ( -0.010 ms)
0: 0x0000000c82785ff2 -> 0x0000000c82784300 -> 0x0000000c8278600d ( -0.309 ms)
After the proposed patch applied the test runs
correctly (~2 hours of testing with a tool above without fails)
Signed-off-by: Ilya Dikariev <dikarill@b-tu.de>
---
drivers/clocksource/arm_arch_timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index a7ff77550e17..3019faa263f5 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -371,7 +371,7 @@ static u64 notrace arm64_858921_read_cntvct_el0(void)
do { \
_val = read_sysreg(reg); \
_retries--; \
- } while (((_val + 1) & GENMASK(8, 0)) <= 1 && _retries); \
+ } while (((_val + 1) & GENMASK(7, 0)) <= 1 && _retries); \
\
WARN_ON_ONCE(!_retries); \
_val; \
--
2.25.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] drivers/clocksource/arm_arch_timer: Tighten Allwinner arch timer workaround
2022-11-09 21:10 ` Ilya Dikariev
@ 2022-11-10 8:31 ` Marc Zyngier
-1 siblings, 0 replies; 6+ messages in thread
From: Marc Zyngier @ 2022-11-10 8:31 UTC (permalink / raw)
To: Ilya Dikariev
Cc: Mark Rutland, Daniel Lezcano, Thomas Gleixner, Samuel Holland,
Chen-Yu Tsai, Jernej Škrabec, linux-sunxi, linux-arm-kernel,
linux-kernel
On Wed, 09 Nov 2022 21:10:49 +0000,
Ilya Dikariev <dikarill@b-tu.de> wrote:
>
> As we know, the Allwinner A64 SoC has a buggy RCU time unit. The
What is RCU?
> workaround named UNKNOWN1 was not sufficient to cover some more buggy
> bunches of this SoC. This workaround diminish the mask to 8 bits instead
> of 9.
>
> An example run of timer test tool https://github.com/smaeul/timer-tools
> on PinePhone device (owns the A64 SoC) gives following result on a non
> patched kernel (cut off):
>
> Running parallel counter test...
> 0: Failed after 5507 reads (0.003578 s)
> 0: 0x0000000c8272cbf1 -> 0x0000000c8272ccff -> 0x0000000c8272cc0e ( 0.011 ms)
> 2: Failed after 14518 reads (0.009248 s)
> 2: 0x0000000c827513f1 -> 0x0000000c82751300 -> 0x0000000c8275140e ( -0.010 ms)
> 3: Failed after 14112 reads (0.008730 s)
> 3: 0x0000000c8274f3f2 -> 0x0000000c8274f300 -> 0x0000000c8274f40d ( -0.010 ms)
> 1: Failed after 12030 reads (0.008409 s)
> 1: 0x0000000c8274abf1 -> 0x0000000c8274acff -> 0x0000000c8274ac0f ( 0.011 ms)
> 1: 0x0000000c827759f2 -> 0x0000000c82775aff -> 0x0000000c82775a0e ( 0.011 ms)
> 0: 0x0000000c8277a9f2 -> 0x0000000c8277aaff -> 0x0000000c8277aa0d ( 0.011 ms)
> 2: 0x0000000c8278f3f1 -> 0x0000000c8278f300 -> 0x0000000c8278f40e ( -0.010 ms)
> 0: 0x0000000c82785ff2 -> 0x0000000c82784300 -> 0x0000000c8278600d ( -0.309 ms)
>
> After the proposed patch applied the test runs
> correctly (~2 hours of testing with a tool above without fails)
2 hours seems like an incredibly small amount of time given that the
existing workaround was believed to be correct. Run it continuously
for a couple of weeks on several different machines with varying
workloads and less us know the outcome.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] drivers/clocksource/arm_arch_timer: Tighten Allwinner arch timer workaround
@ 2022-11-10 8:31 ` Marc Zyngier
0 siblings, 0 replies; 6+ messages in thread
From: Marc Zyngier @ 2022-11-10 8:31 UTC (permalink / raw)
To: Ilya Dikariev
Cc: Mark Rutland, Daniel Lezcano, Thomas Gleixner, Samuel Holland,
Chen-Yu Tsai, Jernej Škrabec, linux-sunxi, linux-arm-kernel,
linux-kernel
On Wed, 09 Nov 2022 21:10:49 +0000,
Ilya Dikariev <dikarill@b-tu.de> wrote:
>
> As we know, the Allwinner A64 SoC has a buggy RCU time unit. The
What is RCU?
> workaround named UNKNOWN1 was not sufficient to cover some more buggy
> bunches of this SoC. This workaround diminish the mask to 8 bits instead
> of 9.
>
> An example run of timer test tool https://github.com/smaeul/timer-tools
> on PinePhone device (owns the A64 SoC) gives following result on a non
> patched kernel (cut off):
>
> Running parallel counter test...
> 0: Failed after 5507 reads (0.003578 s)
> 0: 0x0000000c8272cbf1 -> 0x0000000c8272ccff -> 0x0000000c8272cc0e ( 0.011 ms)
> 2: Failed after 14518 reads (0.009248 s)
> 2: 0x0000000c827513f1 -> 0x0000000c82751300 -> 0x0000000c8275140e ( -0.010 ms)
> 3: Failed after 14112 reads (0.008730 s)
> 3: 0x0000000c8274f3f2 -> 0x0000000c8274f300 -> 0x0000000c8274f40d ( -0.010 ms)
> 1: Failed after 12030 reads (0.008409 s)
> 1: 0x0000000c8274abf1 -> 0x0000000c8274acff -> 0x0000000c8274ac0f ( 0.011 ms)
> 1: 0x0000000c827759f2 -> 0x0000000c82775aff -> 0x0000000c82775a0e ( 0.011 ms)
> 0: 0x0000000c8277a9f2 -> 0x0000000c8277aaff -> 0x0000000c8277aa0d ( 0.011 ms)
> 2: 0x0000000c8278f3f1 -> 0x0000000c8278f300 -> 0x0000000c8278f40e ( -0.010 ms)
> 0: 0x0000000c82785ff2 -> 0x0000000c82784300 -> 0x0000000c8278600d ( -0.309 ms)
>
> After the proposed patch applied the test runs
> correctly (~2 hours of testing with a tool above without fails)
2 hours seems like an incredibly small amount of time given that the
existing workaround was believed to be correct. Run it continuously
for a couple of weeks on several different machines with varying
workloads and less us know the outcome.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] drivers/clocksource/arm_arch_timer: Tighten Allwinner arch timer workaround
2022-11-10 8:31 ` Marc Zyngier
@ 2022-11-10 11:10 ` Ilya Dikariev
-1 siblings, 0 replies; 6+ messages in thread
From: Ilya Dikariev @ 2022-11-10 11:10 UTC (permalink / raw)
To: Marc Zyngier
Cc: Mark Rutland, Daniel Lezcano, Thomas Gleixner, Samuel Holland,
Chen-Yu Tsai, Jernej Škrabec, linux-sunxi, linux-arm-kernel,
linux-kernel
El Thu, 10 Nov 2022 08:31:21 +0000
Marc Zyngier <maz@kernel.org> escribió:
MZ> >
MZ> > As we know, the Allwinner A64 SoC has a buggy RCU time unit. The
MZ>
MZ> What is RCU?
I think I called it wrong. Anyway I mean the HR timer of A64.
MZ>
MZ> > workaround named UNKNOWN1 was not sufficient to cover some more buggy
MZ> > bunches of this SoC. This workaround diminish the mask to 8 bits instead
MZ> > of 9.
MZ> >
MZ> > An example run of timer test tool https://github.com/smaeul/timer-tools
MZ> > on PinePhone device (owns the A64 SoC) gives following result on a non
MZ> > patched kernel (cut off):
MZ> >
MZ> > Running parallel counter test...
MZ> > 0: Failed after 5507 reads (0.003578 s)
MZ> > 0: 0x0000000c8272cbf1 -> 0x0000000c8272ccff -> 0x0000000c8272cc0e ( 0.011 ms)
[......]
MZ> > After the proposed patch applied the test runs
MZ> > correctly (~2 hours of testing with a tool above without fails)
MZ>
MZ> 2 hours seems like an incredibly small amount of time given that the
MZ> existing workaround was believed to be correct. Run it continuously
MZ> for a couple of weeks on several different machines with varying
MZ> workloads and less us know the outcome.
The only A64 machine I own is the Pinephone. First time I did this patch
~9 month ago (on behalf os Samuel). Before it the system suffered hangs
every 15-20 minutes and backward time jumps ~1 time a day.
Since applying of this patch none of above occurred.
To be honest, I never did long tests (weeks). I will put the device
on a probe for some weeks and let you know then.
Best regards,
Ilya
--
запрягай медленно,
едь быстро!
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] drivers/clocksource/arm_arch_timer: Tighten Allwinner arch timer workaround
@ 2022-11-10 11:10 ` Ilya Dikariev
0 siblings, 0 replies; 6+ messages in thread
From: Ilya Dikariev @ 2022-11-10 11:10 UTC (permalink / raw)
To: Marc Zyngier
Cc: Mark Rutland, Daniel Lezcano, Thomas Gleixner, Samuel Holland,
Chen-Yu Tsai, Jernej Škrabec, linux-sunxi, linux-arm-kernel,
linux-kernel
El Thu, 10 Nov 2022 08:31:21 +0000
Marc Zyngier <maz@kernel.org> escribió:
MZ> >
MZ> > As we know, the Allwinner A64 SoC has a buggy RCU time unit. The
MZ>
MZ> What is RCU?
I think I called it wrong. Anyway I mean the HR timer of A64.
MZ>
MZ> > workaround named UNKNOWN1 was not sufficient to cover some more buggy
MZ> > bunches of this SoC. This workaround diminish the mask to 8 bits instead
MZ> > of 9.
MZ> >
MZ> > An example run of timer test tool https://github.com/smaeul/timer-tools
MZ> > on PinePhone device (owns the A64 SoC) gives following result on a non
MZ> > patched kernel (cut off):
MZ> >
MZ> > Running parallel counter test...
MZ> > 0: Failed after 5507 reads (0.003578 s)
MZ> > 0: 0x0000000c8272cbf1 -> 0x0000000c8272ccff -> 0x0000000c8272cc0e ( 0.011 ms)
[......]
MZ> > After the proposed patch applied the test runs
MZ> > correctly (~2 hours of testing with a tool above without fails)
MZ>
MZ> 2 hours seems like an incredibly small amount of time given that the
MZ> existing workaround was believed to be correct. Run it continuously
MZ> for a couple of weeks on several different machines with varying
MZ> workloads and less us know the outcome.
The only A64 machine I own is the Pinephone. First time I did this patch
~9 month ago (on behalf os Samuel). Before it the system suffered hangs
every 15-20 minutes and backward time jumps ~1 time a day.
Since applying of this patch none of above occurred.
To be honest, I never did long tests (weeks). I will put the device
on a probe for some weeks and let you know then.
Best regards,
Ilya
--
запрягай медленно,
едь быстро!
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-11-10 11:34 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-11-09 21:10 [PATCH] drivers/clocksource/arm_arch_timer: Tighten Allwinner arch timer workaround Ilya Dikariev
2022-11-09 21:10 ` Ilya Dikariev
2022-11-10 8:31 ` Marc Zyngier
2022-11-10 8:31 ` Marc Zyngier
2022-11-10 11:10 ` Ilya Dikariev
2022-11-10 11:10 ` Ilya Dikariev
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