Performance

When the 4 was announced, my curiosity (and perhaps yours as well?) was about the flavor of Apple’s A4 SoC inside the phone. The rumor was that the A4 in the iPhone 4 had a full 512MB of memory, compared to 256MB in the iPad’s A4. iFixit took an iPhone 4 apart (with relative ease I might add) and confirmed the presence of 512MB. Look at the A4 in this picture, the Samsung part number on the right edge of the chip starts out K4X4G. The K4X denotes a Samsung mobile DRAM and the 4G refers to its density: 4Gbit or 512MB.

More memory should mean a smoother multitasking experience on the iPhone 4. Remember that iOS 4 keeps all fast task switching enabled apps resident in memory even after you’ve switched away from them. They are only kicked out of memory if you run low or if you force quit them. With more memory you should be able to keep more apps in memory without unwillingly forcing them out. The 512MB of RAM should also give the OS more breathing room in lighter multitasking scenarios, a problem many are already seeing on the iPhone 3GS running iOS 4. In practice the 4 is smoother when running iOS 4. There are still some hiccups but not as bad as on the 3GS, and definitely not as bad as on the 3G. The OS was clearly designed with the iPhone 4 as the performance target.

The big question that remains is what clock speed the iPhone 4’s A4 is running at. The assumption was 1GHz however Apple was very careful not to mention clock speed, unlike at the iPad launch. Saying nothing usually means there’s nothing good to say.

I ran a whole bunch of benchmarks on the iPhone 4 and the iPhone 3GS running iOS 4 to try and figure out what CPU speed we might be dealing with. The early reviews imply that the A4 in the iPhone 4 is running at a speed greater than the 3GS’s 600MHz, but slower than the iPad’s 1GHz. Let’s try and find out what it’s really running at.

We’ll start with the real world tests, first SunSpider. A javascript performance test this benchmark is completely network independent but it measures the performance of the browser as well as the underlying hardware. It is small enough to make memory size differences negligible so between the two iPhones we should be seeing a pure CPU comparison:

The iPhone 4 manages a time that’s 25% faster. Note that this test is just as much about the software stack as it is about CPU/platform performance. The Froyo update makes the Nexus One ridiculously fast in this benchmark. It just shows you how much room there is to improve performance on these Android handsets. The next leapfrog is going to be once the entire Android world moves to 2.2.

Next up is the Rightware BrowserMark. This test combines JavaScript and HTML rendering performance:

BrowserMark spits out an overall score but with no indication of what the score actually means. In this case we’re looking at 18.4% better performance than the iPhone 3GS. The iPad is 34% faster than the 4, which supports the theory of the A4 running at ~750MHz in the new iPhone.

There's also the possibility that the A4 CPU clock varies depending on load and other factors but the run to run consistency in all of our tests seems to indicate otherwise. We also can't ignore the fact that the iPad and iPhone now run vastly different OS revisions. In some cases iOS 4 actually takes a step back in performance compared to iOS 3.2. That undoubtedly makes the iPad vs. iPhone 4 comparison about much more than CPU performance.

Froyo's improved Javascript performance sends the Nexus One nearly to the top of the list here, only bested by the iPad. While Apple has definitely improved performance with the iPhone 4, it seems that it will only take a software update for Android phones to surpass it.

To measure web browsing performance I downloaded a bunch of different web pages and saved as much of them as possible locally on a server. I used WiFi on all of the devices to connect to my local server and timed average load time. I repeated the test at least 3 times and threw out any unusually high or low numbers. Performance was from a clean restart with no additional programs running in memory.

Note that these numbers aren't comparable to other reviews as we've updated software versions on two of the phones. The iPhone 3GS is now running iOS 4 which resulted in some numbers going up while others went down. And the Google Nexus One is running the officially released build of Android 2.2, codenamed Froyo.

What these tests should show is the overall performance of the platform when all network bottlenecks are removed. Obviously hiding in a tunnel under a lead umbrella will make any phone slow, but we’re looking at peak performance here.

The first test is the new AnandTech front page. Here we’ve got tons of images and HTML, meaning we’re stressing both bandwidth and code parsing speed.

The iPhone 4 is no faster than the 3GS (actually slightly slower, but we'll chalk that up to timing variance) here. The Froyo update to the Nexus One makes it lightning quick, almost as fast as the iPad in our first test.

Next up we have the first page of our recent Zotac XBOX HD-ID11 review. The balance shifts from tons of images to more HTML processing:

Here we see more of what I expected: the iPhone 4 is around 25% faster than the 3GS running iOS 4. Android 2.2 running on the Nexus One is basically as fast as the 4.

Using our Print this Review function, this next test loads our entire 2010 15-inch Macbook Pro review. While the other two tests had some flash ad content, this one is completely devoid of it so the HTC phones shouldn’t be penalized:

Here the iPhone 4 is 11% faster than the 3GS and about the speed of the iPad. There are other bottlenecks at play here so we don't get further performance scaling. The Froyo update helps the Nexus One a bit but the iOS devices are still quicker.

Our most intensive test is up next with a load of the Engadget front page:

The Nexus One is ahead of the 4 once more with its Froyo update. And the iPhone 4 is 34% faster than the 3GS.

Our most CPU bound test is up next. I put together a custom page with a ton of tabular content and a single page copy of our 15-inch MBP review to make the load take some time at least.

Surprisingly enough there's no difference between the 3GS and the 4 here, perhaps my test is less CPU bound than I thought. Froyo improves the Nexus One's performance a little bit.

Low Level Synthetic Tests

If we assume that we’re mostly CPU bound in all of these cases (a fair assumption given how fast Atom can run through all of these tests), then we’d be looking at a ~750MHz clock speed for the iPhone 4’s A4 assuming no other architectural changes. That’s actually a pretty big assumption. The A4 is widely believed to be a 45nm SoC using an ARM Cortex A8. At 45nm there should be room for a larger L2 cache than what was used in the iPhone 3GS’s SoC.

Perhaps some more synthetic tests will help us figure out what’s going on. I turned to Geekbench, now available in an iOS version.

Geekbench spit out a number of overall results that gave me a good enough summary of what’s going on to make an educated guess:

The CPU specific tests all indicate the iPhone 4 is around 25% faster than the iPhone 3GS. That would imply at least a 750MHz clock speed if all else is the same. Assuming we don’t get perfect CPU scaling with all of these tests, I’d venture a guess that 800MHz is more accurate. If the A4 does indeed have larger caches however, Apple could get away with a lower clock speed.

The memory results are particularly telling as they all scale very well going to the iPhone 4, better than the CPU results in fact. This could lend credibility to the theory of larger internal caches or perhaps to an improved (faster) memory subsystem.

Unfortunately until we get the iPad on iOS 4 we can't get a better idea of CPU scaling. I'm not even sure how reliable that will be at this point. If Apple was willing to change the amount of memory the A4 package housed between the iPad and iPhone 4, who is to say that it wouldn't have a slightly different design for the iPhone 4 (e.g. larger caches). The designs may not be physically different but we may instead be looking at binning. Given Apple's unwillingness to talk about the architecture here I think the safest bet is that we're looking at an 800MHz ARM Cortex A8 core in the iPhone 4 and a 1GHz core in the iPad.

Why the lower clock? It's all about battery life.

Speakerphone Volume Incredible Battery Life
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  • Thorvald - Wednesday, June 30, 2010 - link

    I understand that you aren't trying to stab at iOS4, but some of these really seem to be a stretch. For example, the iPhone 3G is just about two years old. What two-year old Android phone is running the latest OS with full feature parity as brand-new phones?

    I am quite sure that someone (with more time on their hands than me) could come up with an equally long list of points where Android falls short of iOS4, especially if we are going to be nitpicky about it.

    It would be more nice if there were ways to objectively measure quality of user experience. Specific features are something that can be listed, but implementation counts too.
    Reply
  • Spoelie - Wednesday, June 30, 2010 - link

    You have to understand that that list was NOT originally compiled as a comparison to Android but was the negative part of a "what can you expect with this upgrade" (positives vs negatives) list. The iOS4 upgrade is offered on the 3G and that's why the point has merit: what does the upgrade mean for 3G users?

    However I concur it can read as a comparison since most of these points are Android features on SOME phones (social networking integration for example is mostly part of the proprietary custom UIs like HTC Sense and TouchWiz and not part of Android itself).

    Personally, since I do have an Android phone, it reads more like a "what would I miss if I made the switch" list. But only some of the points.
    Reply
  • darwinosx - Wednesday, June 30, 2010 - link

    Thats a really idiotic list composed by someone who knows nothing about iPhones.

    -Anyone who wants flash on a mobile device is not paying attention.
    -Comments on IOS4 on the 3G are silly. Especially since Apple says its not supported except on the 3GS and 4. Funny how they don't comment on how many Android phones are still on 1.6 and will never be upgraded including some pretty new phones.
    -"True' multi-tasking? I don't think they understand how Android multi-tasking works. It's certainly not "true" multi-tasking as on a desktop os. It's also highly inefficient and a major cause of poor Android phone battery life.
    -Android phones have widgets, which are intrusive and resource consuming because the stock Android OS UI is so awful.
    -There are plenty of ways to USB mass storage with the iPhone.
    -You can mass mark e-mails as read.
    -There are plenty of ways to access the file system not that 99% of users will ever want to.
    -You don't need vibration feedback when touching the screen because the iPhone screen, unlike many Android phones, actually reacts easily to touch.
    -You can do bluetooth file transfers.
    -SMS/MMS has multiple delivery notifications.
    -I play Xvid and Divx all the time and there are multiple third party apps for that.
    -You can add to the iPhone from other apps including Double Twist and others.

    Truly an idiotic list.
    Reply
  • bplewis24 - Wednesday, June 30, 2010 - link

    Whether or not the list is idiotic, you just solidified your own standing with this post. I'm not sure why I even bothered posting to such an idiotic retort.

    Brandon
    Reply
  • mesiah - Thursday, July 1, 2010 - link

    lmao, not to sound like an android fanboy, or even an apple.... haterboy (hmmm new term there.) But your reasoning for alot of those missing features just further backs up the apple fan stereo type.

    Any time an apple device lacks a feature its because "That feature is not needed.' "That feature is useless." or how about "Anyone who wants ___ isn't paying attention."

    But when the next gen phone comes out, and it finally does have those features. You know, the ones everyone else already had and you said you didn't need. You know, like... a camera. You then talk about how your new feature reinvents the phone its self. How "no one has ever done it like apple did."

    Seriously, its pathetic. I know every phone out there has flaws. I also know there are plenty of things apple gets right with the iphone. I will even go as far to admit that smart phones wouldn't be where they are today if it weren't for the iphone. But you people need to admit when you are missing features you should obviously have simply because the all knowing Steve doesn't think you need them. But then again, coming from a company that can admit no wrong, even when their products have a serious design flaw such as the new antenna issue, I can't really expect the followers to act any differently than the ceo.

    "If you want flash you aren't paying attention. If your reception went through the basement you don't know how to hold a phone. And if the AT&T network sucks its because you and all the other people are actually trying to use it."
    Reply
  • strikeback03 - Thursday, July 1, 2010 - link

    One of my friends on facebook posted a screenshot of one of iOS4's great new features...

    ...you can change your wallpaper. Really?
    Reply
  • bregalad - Wednesday, June 30, 2010 - link

    -There are two main reasons to keep Flash off mobile devices: battery life and mouse-overs, a commonly used Flash feature that doesn't work on a touch OS. Given the choice between incomplete support for a resource intensive plug-in and all-day usefulness I'll take that all-day battery life.
    -Multitasking approaches still up for debate
    -iOS 4 runs slowly and lacks features on older hardware - agreed, but does Android do any better? Does your carrier even allow you to upgrade your OS or do you have to get a new phone?
    -Given how much battery life iOS 4 stole from me I really wish there were quick toggles
    -I don't live in any social network. I rarely even launch the facebook app.
    -Something akin to home screen widgets would be very nice
    -Every iPhone and iPod touch has the same sounds, it's terrible in an office with lots of them.
    -Agreed on the mass marking as read
    -Access to the file system is another thing Apple is philosophically opposed to. The iPhone is supposed to be an appliance not a computer.
    -Early iPods had disk mode which was very useful. I wish Apple wouldn't be so inflexible.
    -You want tactile feedback and all day battery life? Maybe next decade.
    -File transfers assumes you have access to the file system and aren't trying to transfer DRM'd files. Not going to happen.
    -I don't know about you, but I've never needed to mass delete contacts from any phone or computer. Do you suffer from multiple personality disorder?
    -Better notifications of all types would be welcome.
    -Smart dialling would be a good feature addition
    -An app whose sole purpose is to play "illegally" downloaded files. Yeah, Steve's going to approve that one 'real soon now'.
    -The dependency on iTunes is a philosophical one. Steve believes your computer is your digital hub, that it contains the master copy of all your stuff. By definition your phone, with its limited storage capacity, contains a subset of that data. I think that makes sense for the vast majority of the public. You're a niche Apple doesn't want to deal with.
    Reply
  • Griswold - Wednesday, June 30, 2010 - link

    Must be nonsenseday today.

    And before you say it, yes I got a 3G and I will replace it with a i4 when they're available around here instead of an android phone as I originally planned, but for other reasons than the fictional ones you just stated.
    Reply
  • Bateluer - Wednesday, June 30, 2010 - link

    Agreed, there are several Android phones that are out now that offer parity with the iPhone 4, and several within 2 months of release that will handily surpass it.

    As usual, Anand's reviews were very well written and detailed, but I'll still pit my year old Moto Droid against any iPhone product. :p
    Reply
  • JAS - Wednesday, June 30, 2010 - link

    As Anand pointed out in his review, the Google/Android operating system feels more like using a computer; and the iPhone (iOS 4) operating system feels more like an appliance. The Android OS is apt to appeal more to the geek than to the "normal mainstream consumer," just as Microsoft Windows is a favorite of people who like to tinker with their computers.

    For better or worse -- each person has to make their own judgment -- Apple's products are defined as much by features that are purposefully withheld as by the cool innovations that are added.
    Reply

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