ASUS Eee Pad Transformer Prime & NVIDIA Tegra 3 Review
by Anand Lal Shimpi on December 1, 2011 1:00 AM ESTCPU Performance
The big news with Tegra 3 is that you get four ARM Cortex A9 cores with NEON support instead of just two (sans NEON) in the case of the Tegra 2 or most other smartphone class SoCs. In the short period of time I had to test the tablet I couldn't draw many definitive conclusions but I did come away with some observations.
Linpack showed us healthy gains over Tegra 2 thanks to full NEON support in Tegra 3:
As expected, finding applications and usage models to task all four cores is pretty difficult. That being said, it's not hard to use the tablet in such a way that you do stress more than two cores. You won't see 100% CPU utilization across all four cores, but there will be a tangible benefit to having more than two. Whether or not the benefit is worth the cost in die area is irrelevant, it only means that NVIDIA (and/or its partners) have to pay more as the price of the end product to you is already pretty much capped.
The bigger benefit I saw to having four cores vs. two is that you're pretty much never CPU limited in anything you do when multitasking. Per core performance can always go up but I found myself bound either by the broken WiFi or NAND speed. In fact, the only thing that would bring the Prime to a halt was if I happened to be doing a lot of writing to NAND over USB. Keyboard and touch interrupts were a low priority at that point, something I hope to see addressed as we are finally entering the era of performance good enough to bring on some I/O crushing multitasking workloads.
Despite having many cores at its disposal, NVIDIA appears to have erred on the side of caution when it comes to power consumption. While I often saw the third and fourth cores fire up when browsing the web or just using the tablet, NVIDIA did a good job of powering them down when their help wasn't needed. Furthermore, NVIDIA also seems to prefer running more cores at lower voltage/frequency settings than fewer cores at a higher point in the v/f curve. This makes sense given the non-linear relationship between voltage and power.
From a die area perspective I'm not entirely sure having four (technically, five) A9 cores is the best way to deliver high performance, but without a new microprocessor architecture it's surely more efficient than just ratcheting up clock speed. I plan on providing a more thorough look at Tegra 3 SoC performance as I spend more time with a fixed Prime, but my initial impressions are that the CPU performance isn't really holding the platform back.
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MiSoFine - Thursday, December 1, 2011 - link
my 2 cents...get a Kindle fire. Easier UI for non tech parents & it's still android; cheaper also. Or a Vizio vTab.I got my Mom a Kindle Fire, kids a vTab (they will at least attempt to try to figure it out) & myself a (preordered) Prime.
steven75 - Saturday, December 3, 2011 - link
Considering the complete lack of Android tablet apps, that doesn't seem wise.Enkur - Thursday, December 1, 2011 - link
What is that android app that shows the per core CPU activity in the screenshot above?Lucian Armasu - Thursday, December 1, 2011 - link
Anand, just remember to note, or even test the real world performance when iPad 3 and other high resolution tablets arrive.In your benchmarks they should be showing even faster performance at 720p with the upcoming faster chips, but that might not be the case in the real world. Remember how low FPS the iPhone 4 got with its 4x the resolution over iPhone 3GS, when tested at native resolution?
That should be happening to iPad 3 and the others, too, even if the chips get faster by then. I would wait until at least 2013 to get a 2k resolution tablet, so I won't be that significantly impacted by it.
Lucian Armasu - Thursday, December 1, 2011 - link
Also is there a way to compare the graphics between Tegra 3 and iPad 2 without comparing the benchmark numbers? Like comparing the best graphics on Tegra 3 versus the best one on iPad 2, and notice the differences between them? I really don't think the benchmark numbers tell the whole truth.I think Tegra 3 games may even look/work better than A5 games, thanks to its quad core CPU, too, but I figure you should be able to tell that better than me since you have both.
vision33r - Thursday, December 1, 2011 - link
I disagree, in PC and Console world, the GPU is the determining factor in game graphics and performance.You can take a Core i7 using HD3000 integrated graphics and compare it with a Core i3 with an ATI 4850 and it will spank the Core i7 in gaming performance.
That's what's happening here is the Tegra 3's GPU is underwhelming from a graphics chip maker.
Very few mobile games imo need even dual core, they need the proper graphics acceleration and that's where Android fragmentation has hurt game development.
They have to code games for the lowest common denominator instead of optimizing games for Tegra.
metafor - Thursday, December 1, 2011 - link
That doesn't necessarily translate to the mobile world. On the desktop side, CPU's have gotten so fast that just about any task a game can throw at it -- physics, AI, audio, etc. -- can be done without bottlenecking the game while the shading/rendering on the GPU is still being pushed.On the mobile side, this may not be true (yet) as the CPU's are -- comparatively -- fairly underpowered against their desktop counterparts. Couple this with the fact that the GPU is taxed to push out less pixels and one could easily see situations where the CPU becomes the bottleneck.
As mobile CPU's get faster -- especially with the A15/Krait generation -- this will become less and less of an issue especially as games make use of NEON to do their computationally heavy tasks and we'll get to a point where the GPU is the only bottleneck left.
But I don't see that happening until we hit the ~2.5GHz dual A15/Krait level.
vision33r - Thursday, December 1, 2011 - link
Very few Android games that I've seen are properly optimized unless they got that Optimized for Tegra logo. Otherwise most games do not take advantage of GPU acceleration.On iOS almost all games has some sort of GPU assist. Take Plants vs Zombies, the iOS version is perfect. The Android HD version has lower animation and graphics.
Almost all Gameloft games perform smoother on iOS than on Android.
metafor - Thursday, December 1, 2011 - link
Well yes. But the point is that with a higher performance CPU or group of CPU's, it is possible to have things that would be bottlenecked in a mobile device -- such as physics, AI, etc. -- be more complex and provide better visuals.Whether or not that has been done is another story. But you can hardly blame application devs for pouring more focus into iOS. The iPad is still what, ~90% of the tablet market? Moreover the App Store brings in way more revenue -- which the developers get a cut of -- than Android Market has thus far.
That will hopefully change over time.
steven75 - Saturday, December 3, 2011 - link
The problem with that theory is iPhones still bring in vastly more revenue for developers than android phones, despite the latter having higher market share.