When level==0(low-performance mode):
1. prefer prev_cpu for rt tasks if prev cpu is fit.
2. make sure that it saves at least 6% of the energy when
migrate tasks from little cpu to big cpu.
When level==2(high-performance mode):
1. do not use EAS path.
2. select big cpu first when system is not overutilized.
3. do not trigger load_balance() when system is not overutilized.
4. prefer prev_cpu for rt tasks if prev cpu is fit.
Test performance improvement for level==2:
1. CONFIG_ROCKCHIP_PERFORMANCE=n
EMMC Random Write(4KB) 25.44MB/s
Antutu:
Total 581266
CPU 133023
GPU 234106
MEM 103602
UX 110535
2. CONFIG_ROCKCHIP_PERFORMANCE=y and level==2
EMMC Random Write(4KB) 44.19MB/s (73.7% improvement)
Antutu:
Total 600483 (3.3% improvement)
CPU 134481 (1.1% improvement)
GPU 234678
MEM 116551 (12.5% improvement)
UX 114773 (3.8% improvement)
Change-Id: I949ac229864eb12159b886b7769e0b489345bef4
Signed-off-by: Liang Chen <cl@rock-chips.com>
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