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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  • horangl3e - Thursday, December 01, 2011 - link

    do you have to post the review as soon as the NDA is lifted? If that is not the case, why not wait a few more days to share the final review? I enjoyed reading what is present right now but was just wondering. Also would you recommend waiting till Win8 tablets if I have no necessity for tablets this very moment? Reply
  • bupkus - Thursday, December 01, 2011 - link

    Also would you recommend waiting till Win8 tablets if I have no necessity for tablets this very moment?

    Sounds like you answered your own question.
    Reply
  • MadMan007 - Thursday, December 01, 2011 - link

    Yes, they have to post as soon as the NDA is lifted because first reviews = page hits. Reply
  • Anand Lal Shimpi - Thursday, December 01, 2011 - link

    It's generally a good idea to have something up when the NDA lifts (plus, if you don't have something up when the NDA lifts manufacturers may think you don't need to be sampled alongside those who do post when the NDA lifts). In the PC space this is rarely an issue since we normally get 7 - 40 days with a product before the NDA lifts. In the mobile space it's a much bigger problem as many reviewers seem to be ok with a 2 - 24 hour testing period (+time for writing). As I mentioned in the article, I fully expect this to change over time (and I'm actively campaigning for it to change), it just doesn't help when ASUS contributes to the problem. To ASUS' credit however, I don't believe this was ultra intentional but it happened nonetheless.

    The tablet space is one area where you should wait if you can. The segment is evolving too quickly.

    Take care,
    Anand
    Reply
  • euler007 - Thursday, December 01, 2011 - link

    You have to give them a pass though, clearly their #1 goal is getting it out to stores before Christmas and they had to compress their entire release schedule, not just the delay between shipping it to reviewers and lifting the NDA.

    Why not do a first impression and an in-depth review after a few days?
    Reply
  • metafor - Thursday, December 01, 2011 - link

    That seems to be the better way of it. The problem with mobile launches is that they do occur very hot-off-the-press in terms of final software/hardware release. They occur so often every year and there's such a race to compete that even if you got a sample very early on, it likely would not have had nearly as complete a software stack. Reply
  • Anand Lal Shimpi - Thursday, December 01, 2011 - link

    This was our first impression post :-P The replacement Prime arrived this morning and I've been working on it since it showed up :) Expect more in the coming days.

    Take care,
    Anand
    Reply
  • aggrobot - Thursday, December 01, 2011 - link

    Sadly, they do. The reason for this is to get the page views. Yes, a more thorough review would be great, and it'll come. For now though, they have to keep up with the competition of suffer the lost visits. Reply
  • Anand Lal Shimpi - Thursday, December 01, 2011 - link

    I felt like I did as best as we could given the WiFi issues of the test sample, more is coming though...

    Take care,
    Anand
    Reply
  • MadAd - Thursday, December 01, 2011 - link

    is it only me that hates that ugly black border around virtually every tablet since the iplod?

    I mean what wrong with having screen to the edge? Somewhere to put your fingers? pfft ill trade that space for working area and hold it at the edge, or if not make it smaller for my pocket
    Reply

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