The Apple iPad 2 Review
by Brian Klug, Anand Lal Shimpi & Vivek Gowri on March 19, 2011 8:01 PM ESTThe Right SoC at the Right Time: Apple's A5
Here's how I know Apple is masterful at marketing. After first showing off the new iPad Apple had tons of press convinced that the company was no longer competing based on specs but rather only interested in delivering an experience. In reality Apple is competing with hardware even more than before, it's just trying to give the public the impression that it's not. After all, Apple doesn't make the vast majority of the technology inside the iPad but it does control the experience. A competitor may be able to ship a dual core Cortex A9 but it can't ship the iOS experience. Is it really a surprise that Apple would downplay what it doesn't have exclusive rights to and instead try to get everyone to focus on what it does? Make no mistake, Apple is very much playing the specs game - in fact it's playing the game harder than anyone else in the industry today.
At the heart of the iPad 2 is a brand new SoC: the Apple A5. Built on what I assume is Samsung's 45nm process the A5 is a much more powerful SoC than it's predecessor the A4.
| Architecture Comparison | |||||||
| ARM11 | ARM Cortex A8 | ARM Cortex A9 | Qualcomm Scorpion | ||||
| Issue Width | single-issue | dual-issue | dual-issue | dual-issue | |||
| Pipeline Depth | 8 stages | 13 stages | 9 stages | 13 stages | |||
| Out of Order Execution | N | N | Y | Partial | |||
| FPU | Optional VFPv2 (not-pipelined) | VFPv3 (not-pipelined) | Optional VFPv3-D16 (pipelined) | VFPv3 (pipelined) | |||
| NEON | N/A | Y (64-bit wide) | Optional MPE (64-bit wide) | Y (128-bit wide) | |||
| Process Technology | 90nm | 65nm/45nm | 40nm | 40nm | |||
| Typical Clock Speeds | 412MHz | 600MHz/1GHz | 1GHz | 1GHz | |||
While the A4 featured a single core ARM Cortex A8, the A5 integrates two ARM Cortex A9s with a total of a 1MB L2 cache. That puts the A5 at a similar level of CPU performance to NVIDIA's Tegra 2 and TI's OMAP 4430. The only insider information I've managed to come across points to A5 featuring ARM's MPE (SIMD/NEON engine) in its A9 cores.
Based on Chipworks' analysis of the Apple A5 die it looks like Apple implemented a dual-channel LP-DDR2 memory controller, similar to TI's OMAP 4430.
| ARM Cortex A9 Based SoC Comparison | |||||
| Apple A5 | TI OMAP 4 | NVIDIA Tegra 2 | |||
| Clock Speed | Up to 1GHz | Up to 1GHz | Up to 1GHz | ||
| Core Count | 2 | 2 | 2 | ||
| L1 Cache Size | 32KB/32KB | 32KB/32KB | 32KB/32KB | ||
| L2 Cache Size | 1MB | 1MB | 1MB | ||
| Memory Interface | Dual Channel LP-DDR2 (?) | Dual Channel LP-DDR2 | Single Channel LP-DDR2 | ||
| NEON Support | Yes (?) | Yes | No | ||
Had it not been for NVIDIA Apple would've had the first shipping dual-core Cortex A9 SoC on the market. This is ultimately why Apple is producing it's own SoCs - most of the players in the SoC space don't seem to be moving fast enough for Apple's hardware schedule. Given the aggressive yearly product cadence I wouldn't be too surprised to see a dual-core Cortex A15 in the Apple A6 a year from now. Remember that much of Apple's success has come from being able to control it's hardware and software development. On the Mac side Apple has an extremely aggressive chip partner with Intel, but with the iDevices there is no equivalent (for now). Until that changes, Apple will continue to produce it's own SoCs. It's not that Apple is designing any of the IP that goes into the SoC, it's that Apple is piecing together what it needs, when it needs it.
We've already gone through the performance offered by the A5 over the A4, but to quickly recap: it's a huge increase. While the original iPad felt slow, the new one feels much faster. I would be lying if I said it was fast enough, but it's way better than the original.
CPU Performance
Taken from our iPad 2 Performance Preview:
| Geekbench 2 - Floating Point Performance | ||||
| Apple iPad | Apple iPad 2 | |||
| Overall FP Score | 456 | 915 | ||
| Mandlebrot (single-threaded) | 79.5 Mflops | 279.1 Mflops | ||
| Mandlebrot (multi-threaded) | 79.4 Mflops | 554.7 Mflops | ||
| Dot Product (single-threaded) | 245.7 Mflops | 221.7 Mflops | ||
| Dot Product (multi-threaded) | 247.2 Mflops | 436.8 Mflops | ||
| LU Decomposition (single-threaded) | 54.5 Mflops | 205.4 Mflops | ||
| LU Decomposition (multi-threaded) | 54.8 Mflops | 421.6 Mflops | ||
| Primality Test (single-threaded) | 71.2 Mflops | 177.8 Mflops | ||
| Primality Test (multi-threaded) | 69.3 Mflops | 318.1 Mflops | ||
| Sharpen Image (single-threaded) | 1.51 Mpixels/s | 1.68 Mpixels/s | ||
| Sharpen Image (multi-threaded) | 1.51 Mpixels/s | 3.34 Mpixels/s | ||
| Blur Image (single-threaded) | 760.2 Kpixels/s | 665.5 Kpixels/s | ||
| Blur Image (multi-threaded) | 753.2 Kpixels/s | 1.32 Mpixels/s | ||
Single threaded FPU performance is multiples of what we saw with the original iPad. This sort of an improvement in single-core performance is likely due to the pipelined Cortex A9 FPU. Looking at Linpack we see the same sort of huge improvement:
Whether this performance advantage matters is another matter entirely. Although there aren't many FP intensive iPad apps available today, moving to the A5 is all about enabling developers - not playing catch up to software.
Geekbench reports the iPad 2 at 512MB of memory, double the original iPad's 256MB. Remember that Apple has to deal with lower profit margins than it'd like with the iPad, but it refuses to cut corners on screen quality so something else has to give.
L2 cache size has also apparently increased from 512KB to 1MB. The L2 cache is shared among both cores and 1MB seems to be the sweet spot this generation.
| Geekbench 2 - Memory Performance | ||||
| Apple iPad | Apple iPad 2 | |||
| Overall Memory Score | 644 | 787 | ||
| Read Sequential (single-threaded scalar) | 340.6 MB/s | 334.2 MB/s | ||
| Write Sequential (single-threaded scalar) | 842.4 MB/s | 1.07 GB/s | ||
| Stdlib Allocate (single-threaded scalar) | 1.74 Mallocs/s | 1.86 Mallocs/s | ||
| Stdlib Write (single-threaded scalar) | 1.20 GB/s | 2.30 GB/s | ||
| Stdlib Copy (single-threaded scalar) | 740.6 MB/s | 522.0 MB/s | ||
Geekbench's memory tests show an improvement in effective bandwidth as well. The biggest improvement is in the stdlib write test which shows a near doubling of bandwidth from 1.2GB/s to 2.3GB/s. Unfortunately this isn't enough data to draw conclusions about bus width or DRAM operating frequency. Given the increases in CPU and GPU performance, an increase in memory bandwidth to go along with the two isn't surprising.
Geekbench shows a healthy increase in integer performance, both in single and multithreaded scenarios. The multithreaded advantage makes sense (two are better than one), but the lead in single threaded tests shows the benefit the A9 can deliver thanks to its shorter pipeline and ability to reorder instructions around stalls.
| Geekbench 2 - Integer Performance | ||||
| Apple iPad | Apple iPad 2 | |||
| Overall FP Score | 365 | 688 | ||
| Blowfish (single-threaded) | 13.9 MB/s | 13.2 MB/s | ||
| Blowfish (multi-threaded) | 14.3 MB/s | 26.1 MB/s | ||
| Text Compression (single-threaded) | 1.23 MB/s | 1.50 MB/s | ||
| Text Compression (multi-threaded) | 1.20 MB/s | 2.82 MB/s | ||
| Text Decompression (single-threaded) | 1.11 MB/s | 2.09 MB/s | ||
| Text Decompression (multi-threaded) | 1.08 MB/s | 3.28 MB/s | ||
| Image Compress (single-threaded) | 3.36 Mpixels/s | 3.79 Mpixels/s | ||
| Image Compress (multi-threaded) | 3.41 Mpixels/s | 7.51 Mpixels/s | ||
| Image Decompress (single-threaded) | 6.02 Mpixels/s | 6.68 Mpixels/s | ||
| Image Decompress (multi-threaded) | 5.98 Mpixels/s | 13.1 Mpixels/s | ||
| Lua (single-threaded) | 172.1 Knodes/s | 273.4 Knodes/s | ||
| Lua (multi-threaded) | 171.9 Knodes/s | 542.9 Knodes/s | ||
On average Geekbench shows a 31% increase in single threaded integer performance over the A4 in the original iPad. NVIDIA told me they saw a 20% increase in instructions executed per clock for the A9 vs. A8 and if we remove the one outlier (text decompression) that's about what we see here as well.
| Geekbench 2 | |||||||
| Overall | Integer | FP | Memory | Stream | |||
| Apple iPad | 448 | 365 | 456 | 644 | 325 | ||
| Apple iPad 2 | 750 | 688 | 915 | 787 | 324 | ||
The increases in integer performance and memory bandwidth are likely what will have the largest impact on your experience. The fact that we're seeing big gains in single as well as multi-threaded workloads means the performance improvement should be universal across all CPU-bound apps.
What does all of this mean for performance in the real world? The iPad 2 is much faster than its predecessor. Let's start with our trusty javascript benchmarks: SunSpider and BrowserMark.
Apple improved the Safari JavaScript engine in iOS 4.3, which right off the bat helped the original iPad become more competitive in this test. Even with both pads running iOS 4.3, the iPad 2 is 80% faster than the original iPad here.
The Motorola Xoom we recently reviewed scored a few percent slower than the iPad 2 in SunSpider as well. Running different OSes and browsers, it's difficult to conclude much when comparing the A5 to Tegra 2.
A bug in BrowserMark kept us from running it for the Xoom review but it's since been fixed. Again we're looking at mostly JavaScript performance here. Rightware modeled its benchmark after the JavaScript frameworks and functions used by websites like Facebook, Amazon and Gmail among others. The results are simply one aspect of web browsing performance, but an important one:
The move from the A4 in the iPad 1 to the A5 in the iPad 2 boosts scores by 47%. More impressive however is just how much faster the Xoom is here. I suspect this has more to do with Google's software optimizations in the Honeycomb browser than hardware, but let's see how these tablets fare in our web page loading tests.
We debuted an early version of our 2011 web page loading tests in the Xoom review. Two things have changed since then: 1) iOS 4.3 came out, and 2) we changed our timing methods to produce more accurate results. It turns out that Honeycomb's browser was stopping our page load timer sooner than iOS', which resulted in some funny numbers when we got to the 4.3/Honeycomb comparison. To ensure accuracy we went back to timing by hand (each test was repeated at least 5 times and we present an average of the results). We also added two more pages to the test suite (Digg and Facebook).
The iPad 2 generally loads web pages faster than the Xoom. On average it's a ~20% increase in performance. I wouldn't say that the improvement is necessarily noticeable when surfing most sites, but it's definitely measurable.
Double the Memory, Still Not Enough
On a Mac or PC if you don't have enough system memory and go to run a new application you'll get a lot of swapping to disk. The OS will write least recently used pages of memory to disk and evict them from main memory, making room for the newly launched application. Memory management in iOS works differently. All applications are required to save their state as soon as they move from the foreground as iOS can evict them from memory at any point in time.
Having more memory in iOS means you can have apps with larger memory footprints or you can keep more apps in memory without forcefully evicting them, but it generally doesn't mean you'll see improved performance.
With the iPad 2 Apple chose to only equip the device with 512MB of LP-DDR2 memory. That's half of what you get in the Motorola Xoom, but twice what you got in the original iPad. This does mean that (as we mentioned earlier) things like web pages can remain in memory longer, although there's no real impact on performance from what we can tell.
If Apple follows its short tradition, we may see more memory in the iPhone 5 and then more in the iPad 3 next year. Display resolution didn't increase so there's no pressure for additional memory there, but Apple is definitely holding developers back by not throwing even more hardware resources at the iPad 2.
Facebook
Twitter
RSS
189 Comments
View All Comments
Shadowmaster625 - Monday, March 21, 2011 - link
If that is true then why not focus on that? I still have yet to read anything on anandtech about remote desktop on a tablet. How powerful does a tablet need to be to stream 1-2 mbps compressed images of my desktop over wifi? I can skin my desktop to make it look more like a mobile OS. Touch commands can be fairly easily emulated and transposed into mouse commands. Audio doesnt require much bandwidth. Only video would present a problem, but even then it really doesnt take all that much hardware to play a video. Yet all I see are horrible implementations of remote desktop.marc1000 - Monday, March 21, 2011 - link
i remember reading here at AT that the Nokia N8 could be used to drive an HDMI display and hooked to an keyboard/mouse, to "simulate" a pc-like experience . and now the Ipad2 does the same thing, but 1 year later.IMHO all that apple does is beautifull, but they charge the price for the "beautifullness" of their products.
well, I just want a tablet/smartphone that works, so I will wait until these prices drop... until then I will live with my Htc HD (1st gen.. ugly!)
Watwatwat - Monday, March 21, 2011 - link
almost feels like i learned something:DJayman30 - Monday, March 21, 2011 - link
Maybe the iPad doesnt fit into a busy techbloggers "workflow" but as a consumer device it's an incredible gadget. My ipad 1 is used daily and has never sat on a shelf unused for more than a few hours. I reach for it first instead of my iPhone or clunky Gateway laptop for 90% of my daily computing needs. It has incredible performance, portability, battery life, and overall utility.I can buy & read books, download and play great games, movies and music quickly and easily. Great Email and web surfing are just icing on the cake! Works great for me!
FYI. iPad 1 costs $399 now.
cotak - Tuesday, March 22, 2011 - link
I am with the staff at anand. I use an iPhone 4. It's nice fo getting a little reading of news etc done. And I have looked at the iPad and I have consider getting one. And likely I will have one but not for myself. It'll be too limiting for me to use. For my fiancee though it's perfect since on a regular week she can go 5 6 days without powering up her computer.So is there s market for tablets? Maybe but I don't think it's big as various peope like to think it could be. And the fall out from that might be pretty big. Nvidia's betting on it, moto has only recently make it back into the black, and rim seems to have concentrated on the playbook over improving their last series of phone release. So maybe some of these players might not be be best stocks to hold for the medium term...
Anyhow tablets are useful for light use. But for people who use their devices/technology enought to justify spending regularly on technology, it might be too small and too slow. And really isn't the repeat buyer the important one I the market? My fiancee could get a iPad 1 and happly use it for the next 6 years without considering buying a new one. If people like that are the market, it's not going to be as big as some people in wall street seems to think.
vshin - Tuesday, March 22, 2011 - link
The one thing I'm surprised that isn't getting as much coverage is that small text is actually harder to read on the Ipad 2 than on the Ipad 1. Some folks chalk this up to being "spoiled" by the Iphone 4's retina display but it's actually because Ipad 2 implements heavy use of anti-aliasing, which can't be configured or turned off. I find my eyes tiring very easily as I browse the web or read on iBook in portrait mode.speedkills - Tuesday, March 22, 2011 - link
I noticed over and over in the review people came back to the point that the current app switching functionality is a very poor user experience. It's too bad Apple isn't enabling the multi-touch gestures for multi-tasking by default as they work very well and while they are not for general release it would be nice to see Anandtech weigh on them to see if they feel they should be included in iOS 5 or if they feel a better implementation is needed.Personally both my girlfriend and I have been using them and absolutely loving them. A four finger swipe up shows the multi-tasking bar instead of having to use the double-tap but 95% of the time a simple four finger swipe left or right is sufficient swapping between your most recently used apps. It makes it very easy to do something like copy a bit of text out of a web page, swipe over to Evernote and make a note, then swipe back to Safari and continue surfing.
It's really too bad Apple chose to hide them by default (my guess is they want to save them for the iPhone release to make iOS 5 look like a bigger jump in functionality) because they are a great and much needed addition to the iPad 2.
Mac Ike - Tuesday, March 22, 2011 - link
First of all this was great and extensive review,thank you very much! I have used Windows computers everyday at Work since Windows 3.1,I enjoy all Computers,but Macs are more stable more elegant,easier-to-use,and hold their value longer! I'm not trying to make Windows-users/lovers change to my preferences. I have not purchased an ipad yet,even though I can see many uses for it,and enjoy using iPads. I want ALL OF THE POWER I could possibly need with me,at all times,so I carry my 17-inch MacBook Pro for those times; when not practical I carry my iphone 4. Serious workloads might send me to my imac,it deprnds on ehere I am and what i need to do or what I can do in the environment that I'm in.Since I enjoyed the ipad 1,it only stands to reason that I would enjoy ipad 2,because the speed increase,cameras,weight-reduction,...can only enhance the experience! I am always amazed by the rude,idiotic,self-centered opinions and insults expressed on these Forums! If YOU don't want or need an ipad (or iPhone/Mac),then buy what YOU like! Why insult someone else,for THEIR DECISIONS or PURCHASES?? it's almost always a cheaper or alternative choices you can make. I give less than a Damn if you like another brand more,or feel that Apple's prices are too high!! If you want a cheaper computer,don't need a tablet,can't see the value of design/workmanship/elegance of OS &Hardware,hardware-software integration,good,buy your low-priced,cheap shit,and leave the rest of us alone,so that we can enjoy what WE LIKE! I don't ask any Apple-Haters or Fence-Sitters to purchase my products for me,so it's just amazing how people feel that you're an Apple-Fan Boy or Girl if you prefer Apple products! If I want a $60,000 Car,and you feel it's worth it(V-8 or not),and you can get a car for $20,000,why should your choice determine mine?? If you Windows-trolls don't like Apple-gear,why come to Apple-topics to complain about SOMEONE ELSE's choices?? Rude,immature,and Stupid!
rice2999 - Tuesday, March 22, 2011 - link
Dear anandThere is nothing about screen brightness setting to go with the battery life testing. Did you use 50% default brightness? Xoom screen is dimmer than ipad/ipad2. Though it can be argued, it is not exactly fair to compare battery life while the screen is on different brightness, since screen is probably the one uses the most battery.
I forget where I saw it, someone else actually used a meter to measure the brightness and adjusted the brightness to the same before testing the battery life.
Sabresiberian - Wednesday, March 23, 2011 - link
Every editor said what I've been saying all along about tablets - they are coolz toyz, but when people start trying to use them, they will find they aren't as handy as either a laptop or a smartphone and they'll be returned or be gathering dust somewhere. Except for niche uses, such as book readers and possibly media device controllers in the home, something like that, tablets are a fad - in my opinion, of course.That being said, they do have innovative technologies I think notebook manufacturers should pay strong attention to and add to their products (netbooks and notebooks). There are things the netbook/notebook can do a tablet's form factor prohibits (add a keyboard to a tablet and it really isn't a tablet any more now, is it?), but there is no reason the notebook should lack any feature a tablet has (except to save money on very low-priced budget models).
As to this thing having enough power to replace a "mainstream" computer if attached to a monitor and keyboard - right. I'll run out right now and buy one to play World of Warcraft on - or isn't that "mainstream" enough for you?
Won't be long now and a device this size will be able to replace what we consider to be a power-house PC these days - but then what will the power-house PC build be like then?
;)