The x86 Power Myth Busted: In-Depth Clover Trail Power Analysis
by Anand Lal Shimpi on December 24, 2012 5:00 PM ESTSunSpider 0.9.1
Now the fun stuff. Doing power profiles of our standard benchmarks gives us good insight into how well each vendor was able to balance peak performance and average power. In general it's ok to burn more power for a short amount of time as long as it means you'll get to sleep quicker. This was one of the fundamentals of the first transition to mobile from the early 2000s.
We already know that Intel completes SunSpider quicker thanks to its improved memory subsystem over the Cortex A9, but it also does so with much better average power (3.70W vs. 4.77W for this chart). A big part of the average power savings comes courtesy of what happens at the very tail end of this graph where the W510 is able to race to sleep quicker, and thus saves a good deal of power.
JavaScript Performance | |||||||
Time in ms (Lower is Better) | Kraken | SunSpider | RIA Bench Focus | ||||
Acer W510 (Atom Z2760 1.8GHz) | 33220.9ms | 730.8ms | 3959ms | ||||
Microsoft Surface (Tegra 3 1.3GHz) | 49595.5ms | 981.1ms | 5880ms | ||||
Samsung ATIV Smart PC (Atom Z2760 1.8GHz) | 33406.0ms | 721.3ms | 3752ms | ||||
Apple iPad 4 (A6X) | 19086.9ms | 834.7ms | - | ||||
Google Nexus 10 (Exynos 5 Dual) | 11146.0ms | 1384.1ms | - |
I also used SunSpider as an opportunity to validate the results from Intel's tablets with my own review samples. To generate this chart I measured power, every second, at the wall with both devices plugged in and with a fully charged battery. The resulting power consumption numbers include the efficiency loss at the AC adapter but the general curve shoud mimic the results above:
Note that the results do generally line up, although measuring at the battery gives more accurate results for the device and using the NI DAQ I was able to get better granularity on the power measurements.
Looking at CPU level power consumption we see a very even match between Atom and Tegra 3. Intel's advantage really comes from being able to complete the workload quicker (0.52W compared to 0.72W on average).
Once again we see a pretty significant difference in power consumption on the GPU rail between these two platforms.
Kraken
Mozilla's Kraken benchmark is a new addition to our js performance suite, and it's a beast. The test runs for much longer than SunSpider, but largely tells a similar story:
RIABench
RIABench's Focus Tests are on the other end of the spectrum, and take a matter of seconds to complete. What we get in turn is a more granular look at power consumption:
163 Comments
View All Comments
yyrkoon - Tuesday, December 25, 2012 - link
same OS, different HAL.Krysto - Monday, December 24, 2012 - link
Good job comparing a last-gen chip like Tegra 3 with Intel's latest Atom chip, Anand. Just because Microsoft is too slow to adopt a cutting edge ARM chip for Windows, doesn't mean Intel is now "toe to toe" with ARM.Compare Nexus 10 and iPad 4 with Clover Trail in GPU performance and price, and then let me know how it went.
croc - Monday, December 24, 2012 - link
People that tend to use terms like 'fact' also seem to be such complete tools...Barnassey - Monday, December 24, 2012 - link
My main thing is why is anand comparing a QUAD core cpu to a DUAL core With hyper-threading cpu? Of course the hyperthreading cpu will use less power.Reikon - Monday, December 24, 2012 - link
Because the dual core CPU still outperforms the quad core one?Barnassey - Monday, December 24, 2012 - link
No because the power consumption will be different. Thats the point im trying to make. Plus anand has shown hes a little biased over the years.r1cky4n - Monday, December 24, 2012 - link
a single atom core is not equivalent to a single a9 coreThe important metric is performance/watt, not watt/core
sseemaku - Tuesday, December 25, 2012 - link
So you want them to disable one of the channels in memory controller and reduce the cache size to match tegra3 for a fair comparison?tempestglen - Monday, December 24, 2012 - link
It seems that "GPU Workload" and ""Photo Enhance" CPU consumption on summary table are inconsistent with diagrams.tempestglen - Monday, December 24, 2012 - link
It also seems that Kraken test diagram of total platform power is just same as cpu only diagram. I guess anandtech posted a wrong picture.Merry Christmas!