Public bug reported:
[Impact]
ACPI-based arm64 systems, such as the Qualcomm QDF2400 and the Hisilicon D05,
do not currently have PMU support. This means that tools like perf are unable
to use the built-in hardware event counters.
[Test Case]
On an ACPI-based arm64 system, run the following commands:
sudo perf list pmu
sudo perf list hw
Without ACPI PMU support, these will be empty.
[Regression Risk]
The changes are restricted to ARM-specific code, other than an added enum value
in linux/cpuhotplug.h. This reduces the non-negligible regression risk to the
ARM architecture.
For ACPI-based ARM platforms, regression risk is negligible because they
did not have PMU support previously. The non-perf related code is
restricted to a change in arch/arm64/kernel/smp.c that saves off
pointers to each CPU's MADT GICC tables. The code is populating a static
array - so pretty low risk (no pointer dereferences, etc).
The most significant regression risk is to ARM non-ACPI platforms. To
mitigate this, we should test this backport on Cavium ThunderX and HP
m400 systems.
** Affects: linux (Ubuntu)
Importance: High
Assignee: dann frazier (dannf)
Status: In Progress
** Affects: linux (Ubuntu Zesty)
Importance: High
Assignee: dann frazier (dannf)
Status: In Progress
** Also affects: linux (Ubuntu Zesty)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu)
Assignee: (unassigned) => dann frazier (dannf)
** Changed in: linux (Ubuntu Zesty)
Assignee: (unassigned) => dann frazier (dannf)
** Changed in: linux (Ubuntu)
Status: New => In Progress
** Changed in: linux (Ubuntu Zesty)
Status: New => In Progress
** Changed in: linux (Ubuntu)
Importance: Undecided => High
** Changed in: linux (Ubuntu Zesty)
Importance: Undecided => High
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https://bugs.launchpad.net/bugs/1689661
Title:
No PMU support for ACPI-based arm64 systems
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Zesty:
In Progress
Bug description:
[Impact]
ACPI-based arm64 systems, such as the Qualcomm QDF2400 and the Hisilicon D05,
do not currently have PMU support. This means that tools like perf are unable
to use the built-in hardware event counters.
[Test Case]
On an ACPI-based arm64 system, run the following commands:
sudo perf list pmu
sudo perf list hw
Without ACPI PMU support, these will be empty.
[Regression Risk]
The changes are restricted to ARM-specific code, other than an added enum
value in linux/cpuhotplug.h. This reduces the non-negligible regression risk to
the ARM architecture.
For ACPI-based ARM platforms, regression risk is negligible because
they did not have PMU support previously. The non-perf related code is
restricted to a change in arch/arm64/kernel/smp.c that saves off
pointers to each CPU's MADT GICC tables. The code is populating a
static array - so pretty low risk (no pointer dereferences, etc).
The most significant regression risk is to ARM non-ACPI platforms. To
mitigate this, we should test this backport on Cavium ThunderX and HP
m400 systems.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1689661/+subscriptions
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