Hi
Does the DVFS of mali400mp make sense?
My platform is ODROID, which equipped with the mali400mp GPU.
I tried to find out how the GPU affect the power consumption of the platform.
The CPU frequency and bus frequency were all fixed.
The mali400mp GPU only supplies two available frequency. They are 160MHz and 267MHz, and their corresponding voltage are 950000 and 1000000 respectively.
mali_dvfs_table mali_dvfs[MALI_DVFS_STEPS]={ /*step 0*/{160 ,1000000 , 950000}, /*step 1*/{267 ,1000000 ,1000000} };
I compared the power consumption of ODROID under different GPU frequencies by fixing them one by one when playing 3D games.
But the power conumption of ODROID varied slightly (less than 5%).
I don't think the result is resonable. Because if less than 5% power saving is achieved, why GPU DVFS ?
According to the papers I have investigated, the power consumption of GPU should be increasingly significant.
But our results show that the power consumption of GPU only occupies a tiny percentage of the platorm's power consumption.
Are there any problems in my experiments ?
Thank you very much.
Beilei Sun
Minyong Kim pointed out that GPU accounts for 12%~20% of total system power consumption in his paper <Accurate GPU Power Estimation for Mobile Device Power Profiling> in 2013.
I think such generalizations are very difficult to make. If someone puts an 8-core Mali-450 alongside a single Cortex-A7 you are going to get a very different relative power load to a 1-core Mali-450 along side a 4-core Cortex-A15. It really depends on many factors: system configuration, what workload you are running, how the GPU was synthesized in silicon, what silicon process, temperature, what content etc - so my gut feel would be that such generalizations are over simplified.
The power consumption of Mali 400MP only take a small part of that of the platform. So the DVFS of Mali 400MP may only have insignificant power saving influence for the platform.
I'd rather have the 5% power saving than none at all =) In most modern devices that translates in to hours more usage on a single battery charge. It should also be noted that on some SoCs the voltage and frequency choice ranges can be much wider than this (the available range depends heavily on silicon process and implementation) - for example a voltage range of 0.7v to 1.0v would give a 50% improvement in energy efficiency per operation, rather than the 10% you see on your platform. In this scenario DVFS for very light workloads would be a large benefit.
But in the future, will GPU become a new power saving bottleneck of smart phone?
See above - it really depends on the specific SoC and content you are running.
HTH, Pete
Thanks very much.
I agree with you that the power saving of GPU DVFS for the platform really depends on the specific SoC and the contents.
But in the future, will GPU become a new power saving bottleneck of smart phone? See above - it really depends on the specific SoC and content you are running.
The GPU in the emerging smartphones tends to be more power critical because of the higher frequency and increasing cores.
If GPU is used to execute tasks that are processed by CPU nowadays in the future, then will GPU become a new power saving bottleneck of smart phone?
Thanks again for your great suggestions.
Best regards!