Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2 2/3] sched: Cleanup SCHED_THERMAL_PRESSURE kconfig entry | From | Dietmar Eggemann <> | Date | Mon, 27 Jul 2020 19:45:49 +0200 |
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On 27/07/2020 16:18, Qian Cai wrote: > On Sun, Jul 12, 2020 at 05:59:16PM +0100, Valentin Schneider wrote: >> As Russell pointed out [1], this option is severely lacking in the >> documentation department, and figuring out if one has the required >> dependencies to benefit from turning it on is not straightforward. >> >> Make it non user-visible, and add a bit of help to it. While at it, make it >> depend on CPU_FREQ_THERMAL. >> >> [1]: https://lkml.kernel.org/r/20200603173150.GB1551@shell.armlinux.org.uk >> >> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> >> --- >> init/Kconfig | 15 ++++++++++++++- >> 1 file changed, 14 insertions(+), 1 deletion(-) >> >> diff --git a/init/Kconfig b/init/Kconfig >> index 0498af567f70..0a97d85568b2 100644 >> --- a/init/Kconfig >> +++ b/init/Kconfig >> @@ -492,8 +492,21 @@ config HAVE_SCHED_AVG_IRQ >> depends on SMP >> >> config SCHED_THERMAL_PRESSURE >> - bool "Enable periodic averaging of thermal pressure" >> + bool >> depends on SMP >> + depends on CPU_FREQ_THERMAL >> + help >> + Select this option to enable thermal pressure accounting in the >> + scheduler. Thermal pressure is the value conveyed to the scheduler >> + that reflects the reduction in CPU compute capacity resulted from >> + thermal throttling. Thermal throttling occurs when the performance of >> + a CPU is capped due to high operating temperatures. >> + >> + If selected, the scheduler will be able to balance tasks accordingly, >> + i.e. put less load on throttled CPUs than on non/less throttled ones. >> + >> + This requires the architecture to implement >> + arch_set_thermal_pressure() and arch_get_thermal_pressure(). >> >> config BSD_PROCESS_ACCT >> bool "BSD Process Accounting" >> -- > > On arm64 linux-next (20200727), > > https://gitlab.com/cailca/linux-mm/-/blob/master/arm64.config > > WARNING: unmet direct dependencies detected for SCHED_THERMAL_PRESSURE > Depends on [n]: SMP [=y] && CPU_FREQ_THERMAL [=n] > Selected by [y]: > - ARM64 [=y]
Not sure, but:
(1) do we wan to let people enable SCHED_THERMAL_PRESSURE for arm64 so arm64 can potentially run w/o a CPU freq cooling device?
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 2d4abbc9f8d0..baffe8b66da2 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -192,7 +192,6 @@ config ARM64 select PCI_SYSCALL if PCI select POWER_RESET select POWER_SUPPLY - select SCHED_THERMAL_PRESSURE select SPARSE_IRQ select SWIOTLB select SYSCTL_EXCEPTION_TRACE diff --git a/init/Kconfig b/init/Kconfig index 37b089f87804..8b36e07fb230 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -492,7 +492,7 @@ config HAVE_SCHED_AVG_IRQ depends on SMP
config SCHED_THERMAL_PRESSURE - bool + bool "Thermal pressure accounting" depends on SMP depends on CPU_FREQ_THERMAL help Or
(2) should SCHED_THERMAL_PRESSURE for arm64 be enabled by default?
But then it makes no sense to allow the removal of CONFIG_CPU_FREQ_THERMAL.
linux-next/master$ make ARCH=arm64 defconfig
// Remove CONFIG_CPU_FREQ_THERMAL linux-next/master$ grep CPU_FREQ_THERMAL .config # CONFIG_CPU_FREQ_THERMAL is not set
linux-next/master$ make scripts/kconfig/conf --syncconfig Kconfig
WARNING: unmet direct dependencies detected for SCHED_THERMAL_PRESSURE Depends on [n]: SMP [=y] && CPU_FREQ_THERMAL [=n] Selected by [y]: - ARM64 [=y]
WARNING: unmet direct dependencies detected for SCHED_THERMAL_PRESSURE Depends on [n]: SMP [=y] && CPU_FREQ_THERMAL [=n] Selected by [y]: - ARM64 [=y]
WARNING: unmet direct dependencies detected for SCHED_THERMAL_PRESSURE Depends on [n]: SMP [=y] && CPU_FREQ_THERMAL [=n] Selected by [y]: - ARM64 [=y] HOSTCC scripts/dtc/dtc.o
--- There is a similar issue with arm.
I would prefer for (1).
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