| Message ID | 20200924123937.20938-1-ionela.voinescu@arm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | condition EAS enablement on FI support | expand |
On Thursday 24 Sep 2020 at 13:39:34 (+0100), Ionela Voinescu wrote: > Given the maturity gained by cpufreq-based Frequency Invariance (FI) > support following the patches at [1], this series conditions Energy > Aware Scheduling (EAS) enablement on a frequency invariant system. > > Currently, EAS can be enabled on a system without FI support, leading > to incorrect (energy-wise) task placements. As no warning is emitted, > it could take some debugging effort to track the behavior back to the > lack of FI support; this series changes that by disabling EAS > (and advertising it) when FI support is missing. > > The series is structured as follows: > - 1/3 - create function that can rebuild the scheduling and EAS' > performance domains if EAS' initial conditions change > - 2/3 - condition EAS enablement on FI support > - 3/3 - arm64: rebuild scheduling and performance domains in the > case of late, counter-driven FI initialisation. I'm still reading through this, but shouldn't patch 2 and 3 be swapped? Otherwise we have a weird state at patch 2 where EAS will fail to start (IIUC), which might not be ideal for bisection. Thoughts? Cheers, Quentin
On Thursday 24 Sep 2020 at 14:37:27 (+0100), Quentin Perret wrote: > On Thursday 24 Sep 2020 at 13:39:34 (+0100), Ionela Voinescu wrote: > > Given the maturity gained by cpufreq-based Frequency Invariance (FI) > > support following the patches at [1], this series conditions Energy > > Aware Scheduling (EAS) enablement on a frequency invariant system. > > > > Currently, EAS can be enabled on a system without FI support, leading > > to incorrect (energy-wise) task placements. As no warning is emitted, > > it could take some debugging effort to track the behavior back to the > > lack of FI support; this series changes that by disabling EAS > > (and advertising it) when FI support is missing. > > > > The series is structured as follows: > > - 1/3 - create function that can rebuild the scheduling and EAS' > > performance domains if EAS' initial conditions change > > - 2/3 - condition EAS enablement on FI support > > - 3/3 - arm64: rebuild scheduling and performance domains in the > > case of late, counter-driven FI initialisation. > > I'm still reading through this, but shouldn't patch 2 and 3 be swapped? > Otherwise we have a weird state at patch 2 where EAS will fail to start > (IIUC), which might not be ideal for bisection. > > Thoughts? I probably invented myself reasons for not doing it, like: without 2/3, 3/3 does not make any sense having and the scenario at 3/3 is currently unlikely. But it would definitely make it safer, so I'll change the order. Thanks, Ionela. > > Cheers, > Quentin
Given the maturity gained by cpufreq-based Frequency Invariance (FI) support following the patches at [1], this series conditions Energy Aware Scheduling (EAS) enablement on a frequency invariant system. Currently, EAS can be enabled on a system without FI support, leading to incorrect (energy-wise) task placements. As no warning is emitted, it could take some debugging effort to track the behavior back to the lack of FI support; this series changes that by disabling EAS (and advertising it) when FI support is missing. The series is structured as follows: - 1/3 - create function that can rebuild the scheduling and EAS' performance domains if EAS' initial conditions change - 2/3 - condition EAS enablement on FI support - 3/3 - arm64: rebuild scheduling and performance domains in the case of late, counter-driven FI initialisation. This series is dependent on the patches at [1] and based on linux-next 20200918. [1] Most recent version at: https://lore.kernel.org/lkml/20200901205549.30096-1-ionela.voinescu@arm.com/ Ionela Voinescu (3): sched/topology,schedutil: wrap sched domains rebuild sched/topology: condition EAS enablement on FIE support arm64: rebuild sched domains on invariance status changes arch/arm64/include/asm/topology.h | 1 + arch/arm64/kernel/topology.c | 10 ++++++++++ include/linux/sched/topology.h | 1 + kernel/sched/cpufreq_schedutil.c | 9 +-------- kernel/sched/topology.c | 26 +++++++++++++++++++------- 5 files changed, 32 insertions(+), 15 deletions(-) base-commit: b652d2a5f2a4e93d803cc33eb57fdc41ee528500 prerequisite-patch-id: 592324cdfe0735a845d827d23f4d042b66e480ae prerequisite-patch-id: b232a586616b573b7fc320df2dcf4783f26dc169 prerequisite-patch-id: 8a8238e55f4e522eb0ee44c1d4a083cac019959a prerequisite-patch-id: 8edd7fc97f15c7f737339d3e07dbcd6c6d99d986 prerequisite-patch-id: b24b28cd2ec4c929b770f5dd3eeb30f839f8d6ab