The commit 05484e098448 ("sched/topology: Add SD_ASYM_CPUCAPACITY
flag detection") to automatically detect asymmetric CPU capacity
has been merged into v4.20-rc1, so I will post this patch series
as v2 again.
These add the scheduler information to be aware cpu capacity. Some
R-Car SoCs have big LITTLE architecture(e.g. CA57/CA53). It has a
difference performance/power consumption for each CPUs.
As the scheduler will be aware the capacity of CPU, the scheduler is
balancing so that the free capacity of each CPU is even. This means
that it aggressively migrates tasks to big CPUs(e.g. CA57) with large
capacity in case of the system load is low and middle, the performance
of user application is improved than before.
Since most users for IVI are using CPU with performance oriented than
power consumption, this change will benefit for their use-cases. Some
benchmark is improved as an example below.
UnixBench (1 parallel) on r8a7796 SoC (CA57x2 + CA53x4) :
before after
- Dhrystone 2 using register variables 4777159 11353624 +58%
- Double-Precision Whetstone 866 1218 +29%
- Execl Throughput 728 920 +21%
- File Copy 1024 bufsize 2000 maxblocks 69405 115962 +40%
- File Copy 256 bufsize 500 maxblocks 21404 28685 +25%
- File Copy 4096 bufsize 8000 maxblocks 102749 159978 +36%
- Pipe Throughput 93876 150848 +38%
- Pipe-based Context Switching 27257 25317 -8%
- Process Creation 1885 2292 +18%
- Shell Scripts (1 concurrent) 135 137 +1%
- Shell Scripts (8 concurrent) 35 34 -3%
- System Call Overhead 99169 140146 +29%
- System Benchmarks Index Score 112 152 +26%
UnixBench (8 parallel) on r8a7795 SoC (CA57x4 + CA53x4) :
before after
- Dhrystone 2 using register variables 64686060 64472624 0%
- Double-Precision Whetstone 8380 8423 +1%
- Execl Throughput 5856 6147 +5%
- File Copy 1024 bufsize 2000 maxblocks 142923 164482 +13%
- File Copy 256 bufsize 500 maxblocks 46257 51344 +10%
- File Copy 4096 bufsize 8000 maxblocks 360398 393339 +8%
- Pipe Throughput 974106 972545 0%
- Pipe-based Context Switching 162455 146567 -11%
- Process Creation 10164 9659 -5%
- Shell Scripts (1 concurrent) 317 317 0%
- Shell Scripts (8 concurrent) 30 31 +3%
- System Call Overhead 897596 899274 0%
- System Benchmarks Index Score 523 534 +2%
based on renesas-devel-20181105-v4.20-rc1
v1 -> v2:
- Consolidate two patches for r8a7795 and r8a7796 into one patch
- Add the formula for capacity-dmips-mhz into description
- Remove the static setting of SD_ASYM_CPUCAPACITY for R-Car
Gaku Inami (2):
arm64: dts: renesas: Add CPU topology on R-Car Gen3 SoCs
arm64: dts: renesas: Add CPU capacity-dmips-mhz
arch/arm64/boot/dts/renesas/r8a7795.dtsi | 40 ++++++++++++++++++++++++++++++++
arch/arm64/boot/dts/renesas/r8a7796.dtsi | 32 +++++++++++++++++++++++++
2 files changed, 72 insertions(+)
--
2.7.4
