[v2,3/3] arm64: disable ACPI PPTT support temporarily

Message ID 1528209304-3280-3-git-send-email-sudeep.holla@arm.com
State New
Headers show
Series
  • [v2,1/3] Revert "arm64: topology: divorce MC scheduling domain from core_siblings"
Related show

Commit Message

Sudeep Holla June 5, 2018, 2:35 p.m.
Currently, ARM64 doesn't support updating the CPU topology masks on
CPU hotplug operations. ACPI PPTT support rely on that missing feature
which is technically not incorrect. Instead of reverting all the PPTT
support, let's keep it simple and disable ACPI PPTT support on ARM64
for time-being until the topology updates are added for CPU hotplug
operations.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

---
 arch/arm64/Kconfig | 1 -
 1 file changed, 1 deletion(-)

-- 
2.7.4

--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Comments

Sudeep Holla June 5, 2018, 3:27 p.m. | #1
On 05/06/18 16:02, Rafael J. Wysocki wrote:
> On Tue, Jun 5, 2018 at 4:35 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:

>> Currently, ARM64 doesn't support updating the CPU topology masks on

>> CPU hotplug operations. ACPI PPTT support rely on that missing feature

>> which is technically not incorrect. Instead of reverting all the PPTT

>> support, let's keep it simple and disable ACPI PPTT support on ARM64

>> for time-being until the topology updates are added for CPU hotplug

>> operations.

> 

> When is that going to happen?

> > Nobody else uses PPTT now.

> 


No we need it on ARM64. I have even the fixes for the original issue
but it's bit invasive and too late as we are already in the merge
window. It needs to be tested on NUMA platforms, I have asked for that
explicitly.

-- 
Regards,
Sudeep
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Jeremy Linton June 5, 2018, 4:38 p.m. | #2
Hi,

On 06/05/2018 10:27 AM, Sudeep Holla wrote:
> 

> 

> On 05/06/18 16:02, Rafael J. Wysocki wrote:

>> On Tue, Jun 5, 2018 at 4:35 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:

>>> Currently, ARM64 doesn't support updating the CPU topology masks on

>>> CPU hotplug operations. ACPI PPTT support rely on that missing feature

>>> which is technically not incorrect. Instead of reverting all the PPTT

>>> support, let's keep it simple and disable ACPI PPTT support on ARM64

>>> for time-being until the topology updates are added for CPU hotplug

>>> operations.

>>

>> When is that going to happen?

>>> Nobody else uses PPTT now.

>>

> 

> No we need it on ARM64. I have even the fixes for the original issue

> but it's bit invasive and too late as we are already in the merge

> window. It needs to be tested on NUMA platforms, I have asked for that

> explicitly.

> 


So, there is a lot simpler fix for this, and its to remove the numa mask 
dependency from the scheduler domain building. That is just a couple 
line fix, and it reverts !ACPI to its original behavior, while the ACPI 
LLC building will work around the NUMA in package issue that caused 
patch 12/12 as the machine in question doesn't have a LLC crossing numa 
domains.
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 9fd4a8ccce07..98a5c78a80f9 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -7,7 +7,6 @@  config ARM64
 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
 	select ACPI_MCFG if ACPI
 	select ACPI_SPCR_TABLE if ACPI
-	select ACPI_PPTT if ACPI
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_DEBUG_VIRTUAL
 	select ARCH_HAS_DEVMEM_IS_ALLOWED