Hi Viresh, > On 22 May 2013 15:57, Lukasz Majewski <l.majewski@xxxxxxxxxxx> wrote: > >> On 3 May 2013 19:37, Jonghwa Lee <jonghwa3.lee@xxxxxxxxxxx> wrote: > > > I think, that overclocking support is crucial here. As you pointed > > out > > - ondemand and conservative benefit from it. Therefore, I would urge > > for its mainline acceptance. > > > > (code for reference) > > http://thread.gmane.org/gmane.linux.kernel/1484746/match=cpufreq > > > > In this RFC (patch 1/3), I've decided to put the burden of > > overclocking support to platform code (cpufreq/exynos-cpufreq.c and > > cpufreq/exynos4x12-cpufreq.c). > > > > Those changes aren't intrusive for other boards/archs. Moreover > > overclocking is closely related to processor clocking/power > > dissipation capabilities, so SoC specific code is a good place for > > it. > > > > > > What DO need a broad acceptance is the overclocking API proposed at: > > include/linux/cpufreq.h > > > > This introduces interface to which others will be bind. It > > shouldn't be difficult to implement overclocking at other SoCs (as > > it was proposed for Exynos). > > > > Feedback is welcome, since I might have overlooked oddities present > > at other SoCs. > > Hi.. > > I am not talking about the minute details here... for example I > didn't like the way overclocking support is implemented... It has to > be a bit more framework oriented then driver... > > What I am thinking right now is if it is worth to add both the > features you are trying. i.e. overclocking and LAB.. > > So, requested you to give some figures... of ondemand with and without > overclocking... Leave LAB for now... > > Then we can give LAB a try with above... Test HW Exynos4412 (4 Cores): Kernel 3.8.3 Ondemand max freq: 1.4 GHz Overclock max freq: 1.5 GHz Ondemand improvement with and without overclocking (called by us TurboBoost - TB): Dhrystone has been built according to: http://zenit.senecac.on.ca/wiki/index.php/Dhrystone_howto It's Makefile is also attached. ------------------------------------------------ Dhrystone # of Threads 1 2 3 4 ondemand 2054794 2061855 2097902 2090592 ondemand + TB 2290076 2205882 2281368 2290076 Improvement: 10% 7% 8% 9% ------------------------------------------------- Electric charge [C] (Avg) [A] * [second] # of Threads 1 2 3 4 ondemand 1,334 1,837 2,296 3,096 ondemand + TB 1,401 2,2025 2,907 4,34976 Power cost: 5% 17% 21% 29% ------------------------------------------------- Execution time [second] # of Threads 1 2 3 4 ondemand 2,827 2,8 2,787 2,872 ondemand + TB 2,622 2,694 2,667 2,76 Speedup: -7% -4% -4% -4% ------------------------------------------------- "Real life" example: time tar -czf linux-3.9.1.tar.gz linux-3.9.1/ Avg current[mA] Time[s] Ondemand: 460 153 Ondemand + TB: 512 144 Result: +10% -6% Conclusion: The main use case for TB is to speed up execution of tasks packed to one core. Other cores are then in IDLE state. For a single core we can safely overclock, since we will not exceed its power consumption and thermal limits. -- Best regards, Lukasz Majewski Samsung R&D Poland (SRPOL) | Linux Platform Group
Attachment:
Makefile
Description: Binary data
