CPU 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:

Linpack - Single-threaded

Linpack - Multi-threaded

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.

SunSpider JavaScript Benchmark 0.9.1

Rightware BrowserMark

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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  • Penti - Thursday, December 01, 2011 - link

    It looks like they have finally a pretty good product and software, they should dump the Eee pad and the redundant awkward name now and it would be even better :)

    Would love to see better optimized software, but this is what you could have expected plus with a great screen and I wonder how well it would work as a thin-client with Citrix? Keyboard and touchpad should make it a pretty good experience, does it? Chromebooks can just forget it any way :) Here we have form factor, local software, multimedia (Chromebooks are not even having accelerated H.264 as standard) and so on. With keyboard docked and standard, and not just a browser that was obvious would be replaced by a Android distribution of some kind any way. Maybe that time is now. Even though I wouldn't except Asus to complete that process. Fun to see them kinda getting there act together though.
    Reply
  • Malih - Thursday, December 01, 2011 - link

    I agree that Eee is an awful name, especially for a flagship/cutting-edge product.
    Eee is associated with low-end Atom netbooks, since that's the first device that uses the name. And I always hate that Samsung name their mobile devices Galaxy.

    IMHO, the name Zenbook sounds good, maybe they should invent something consistent with that for their top-line tablet, Zenpad?
    Reply
  • Penti - Friday, December 02, 2011 - link

    Zenbook is still kinda awkward but it's better, ZenPad doesn't do anything for me and sounds silly. Transformer Prime is a pretty good name. Transformer might cause some confusion though, if they decide to release one without any keyboard attachment. Their Windows tablet PCs (slates as of now) might as well get some updated finish and release as a Zenbook slate though. Reply
  • MamiyaOtaru - Thursday, December 01, 2011 - link

    "The 16:9 panel measures 10.1-inches diagonally, giving it a larger surface area than the iPad 2's 9.7-inch 4:3 display. "

    If you do your math, this isn't actually true. A 10.1" 16:9 display has a surface area of 43.58", while a 9.7" 4:3 display has a surface area of 45.17". This is one of the main reasons behind widescreen, they get to trumpet a larger diagonal measurement while actually saving costs on smaller total area. I am a little disappointed you fell for it.
    Reply
  • MamiyaOtaru - Thursday, December 01, 2011 - link

    some numbers you can plug in for verification (rounding all around!):
    16:9 10.0" display has sides of 8.8 and 4.951. 8.8/4.95 ~= 16/9 (correct ratios). 8.8² + 4.95² ~= 10.1² (correct dimensions for given diagonal, shown via pythagorean theorem).
    area then: 8.8*4.95 = 43.96.

    4:3 9.7" display has sides of 7.76 and 5.82. 7.76/5.82 ~= 4/3 (correct ratios). 7.76²+5.81² ~= 9.7² (correct dimensions for given diagonal, shown via pythagorean theorem).
    area: 7.76*5.81=45.09.

    45.09 is larger than 43.96. Ipad2 has a screen with a larger surface area. Run the numbers. Do it without dropping as many places as I did in this post, result will be the same. Again, disappointing

    (I don't have a horse in this race, I own no Apple products. I do hate widescreen monitors though)
    Reply
  • MamiyaOtaru - Thursday, December 01, 2011 - link

    interestingly, the gap was closed somewhat when I dropped more places in typing up the second post. The first is more accurate, and the gap is bigger. But they both show the ipad as having more surface area, and that will hold true with pretty much whatever level of exactitude one wishes to calculate it Reply
  • Anand Lal Shimpi - Thursday, December 01, 2011 - link

    It's actually a 16:10 panel, my statement was incorrect. But the Prime's display measures roughly 8.5" x 5.25". The iPad 2 by comparison measures approximately 7.75" x 5.75". 44.625 in^2 vs. 44.5625 in^2, giving the Prime a slightly larger display (albeit negligible). Reply
  • Solandri - Thursday, December 01, 2011 - link

    At 9.7" diagonal and 4:3 aspect ratio, the iPad 2's screen is 7.76" x 5.82".

    At a 10.1" diagonal and 16:10 aspect ratio, the Prime's display is 8.56" x 5.35".
    Reply
  • Solandri - Thursday, December 01, 2011 - link

    Anand's math is right. His aspect ratio is wrong. The Transformer Prime has a 1280x800 screen, which is 16:10, not 16:9. At a 16:10 aspect ratio, you end up with 45.85 square inches of surface area.

    Personally I think 16:10 is the "right" aspect ratio for a multifunction device. You waste10% of the screen when displaying a 16:9 video. A 4:3 device wastes 25% of the screen. The extra width is nicer for web browsing too.

    Where the 4:3 screen does better is displaying pages scanned from paper or magazines. Subtracting a 1-inch margin along all four sides, a 4:3 screen wastes 4% of its screen displaying a Letter-sized sheet of paper, while a 16:10 wastes 13%. (With A4 paper and 2-cm margins, it's reversed. The 4:3 wastes 12%, the 16:10 screen wastes 6%.)

    But that's counter to the whole point of tablets - to free us from the shackles of a paper-bound world. As a media consumption device, I think 16:10 is the better aspect ratio. It's almost exactly the golden ratio too (1.62), so most art which is produced will fit in it better.
    Reply
  • GnillGnoll - Friday, December 02, 2011 - link

    For browsing the web and reading, portrait orientation is often a better fit. Though it requires a certain minimum width and resolution to work really well. Reply

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