Apple's iOS 4 Explored
by Anand Lal Shimpi on June 22, 2010 3:27 AM EST- Posted in
- Smartphones
- Apple
- iOS 4
- Gadgets
- Mobile
Grand Central Dispatch
While not listed as a marketing feature of iOS 4, Apple’s developer guide lists Grand Central Dispatch as a new feature of the OS. Those of you who are familiar with Mac OS X 10.6 will know Grand Central Dispatch as a task management/thread spawning core that aims to simplify multithreaded development while boosting thread utilization on platforms. The developer focuses on splitting up tasks in a sensible fashion rather than juggling n-number of threads and GCD deals with spawning the appropriate number of threads for the system.
This is of course a non-issue on any current iPhone, including the new 4th generation model, but it does make sense for Apple to introduce it now. While the iPhone 4 is a single core/single thread device, the 5th generation iPhone will almost certainly have two cores. The ramp to multithreading on mobile devices will be much quicker than what we saw on desktop PCs, mostly thanks to the fact that the leap on the PC is largely complete.
With Hyper Threading and other SMT technologies on the horizon for smartphone SoCs it’s not far fetched to see the majority of high end smartphones capable of executing 2 - 4 threads in the next 3 years.
Resolution Independent Development
Everyone should know by now that the iPhone 4 will have a ridiculously dense screen with over 600,000 pixels in an area the same as the past three iPhones. The 960 x 640 resolution is an even 2x increase in both directions compared to the previous iPhones, however developers shouldn’t have to do anything different to target their apps to the various iPhone revisions.
Apps draw to a virtual screen which is then mapped to the physical screen by the OS. Resolution, at least on the iPhone, doesn’t appear to be a concern of the developer. Obviously apps and games with higher levels of detail will take advantage of the iPhone 4’s available resolution but a re-write or any modifications to existing apps aren’t necessary.
Game Center
Apple made two bold announcements at its iOS 4 unveiling: iAds and the iOS Game Center. The former went after Google, the latter, Microsoft, Nintendo and Sony.
The iOS Game Center is essentially Xbox Live for Apple iOS devices. Users will be allowed to create their own online identities (similar to Xbox Live profiles) and can play with or against one another with matchmaking, track achievements, chat with one another and basically do anything you’d want to do in an online gaming service. Eventually all iOS games will use and support the Game Center, just like there’s some amount of Xbox Live integration with all Xbox 360 games today.
When I first saw Unreal Engine running on the iPod Touch I mentioned that within 3 - 5 years we’d have the power of an Xbox 360 in a device the size of an iPhone. By introducing the Game Center early on, Apple is creating the foundation for what it ultimately hopes the iOS platform will turn into. Apple also has an advertising platform built in should it want to sell in game ads, hmm...
The Game Center wasn’t ready for launch with iOS 4 however developers are given full access to it. I’d expect a follow up launch later this year once it’s ready.
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rallstarz - Tuesday, June 22, 2010 - link
Forgive me for peeking at your email Anand, but I'd be excited about a fro-yo review on anandtech.... maybe fro-yo making machines, fro-yo flash freezers, fro-yo dispensers...Stuka87 - Tuesday, June 22, 2010 - link
Over all I like the upgrade. My phone feels more snapping in several areas (3GS). However, I have two big issues.1: In Mail, I want a "Mark All Read" option. I tgets *SO* old having to go through 30-40 emails because I read them on another device. Not an issue with my Exchange mail, but is a major issue with my POP3 mail.
2: I wish I could exclude some apps from multi tasking. Because now I find myself running 4-5 apps at the same time. And most of them are apps that don't need two. Like weather, or calculator. I would love it if I could say "Dont ever multi-task this app". The same could be applied to some games.
metafor - Tuesday, June 22, 2010 - link
"We still need faster SoCs and more power efficient platforms to make multitasking work on smartphones. I say faster SoCs because one of the best ways to improve power efficiency is to complete tasks quicker so that the CPU can return to an idle state.Because current smartphone SoCs don’t have the level of performance needed to quickly execute a ton of extra instructions and get back to sleep, smartphone OSes have to keep background tasks to a minimum. For the most part you don’t have to worry about what applications you have open on your notebook, your CPU is efficient enough and you have enough battery power to churn through any instructions idle apps may be throwing at it. We’re not quite there yet in smartphones."
I'm afraid this isn't true. The only difference between a netbook processor and a smartphone processor is that the former is running off of a relatively honking battery. Having the CPU "finish the task faster" is absolutely not a power advantage.
Let's break down the 2 main areas of power usage for a CPU:
1. Leakage. Here, you can make the argument that if a CPU is active longer, it suffers more total energy that is leaked between VDD and GND. However, this is almost entirely offset and in most cases overshadowed by the fact that a faster CPU (running either at a higher frequency, has more parallel execution resources, or runs on faster transistors) will always be significantly leakier than their slower counterparts. Leakage increases with the square of voltage and as everyone will tell you, when a CPU ramps up in frequency, it will scale up its voltage.
2. Dynamic current. This only gets worse at faster frequencies. Whether you're charging/discharging 500 million times a second (500MHz) or 1 billion times a second (1GHz), the same tasks requires the same number of charges/discharges whether it happens in 1 second or 2 seconds. The same amount of energy to perform the work is used. However, as mentioned before, to make a chip run faster, you'll have to also up the voltage and/or use leakier (but faster) transistors.
In fact, the argument for dual-core being more power efficient is that in the case where 2 cores running at 500MHz doing the same amount of work (assuming you're running, say, 2 tasks that would otherwise be context switched in the same CPU) as 1 core at 1 GHz, the 2-core solution would draw less power since a core running at 500MHz uses less than half the power of a 1GHz core.
You are absolutely right in that the limitations of multitasking has to due with power efficient CPU's and it is a compelling argument for multi-core cell phone SoC's and perhaps even heterogeneous multi-core SoC's. Luckily, we'll be seeing those soon enough in the next year or so.
Matt Campbell - Tuesday, June 22, 2010 - link
Angry Birds is a great game - but why do you have both the Lite and Full version installed in the screen shot? :)So far, my biggest likes of iOS4 are the responsiveness (3GS definitely feels faster) and the email threads, which really help on my Exchange account. I read a lot of eBooks on Stanza and will probably stick with that for the short term.
SunSamurai - Friday, June 25, 2010 - link
Because he tried it before he buyed it? ;)Polizei - Tuesday, June 22, 2010 - link
I love that Anand is bumpin the 50 cent during his Iphone interview. Funny choice :Dsynaesthetic - Tuesday, June 22, 2010 - link
Anyone know if these ads show up on the iPod touch 3G upgraded to iOS 4?If so I probably won't buy a Touch...
I don't understand why *anyone* would prefer ads to paying more for software. Seriously, it's not worth it to me. TV commercials are bad enough.
SunSamurai - Friday, June 25, 2010 - link
You dont understand why people dont want to spend money when they dont have to?jasperjones - Tuesday, June 22, 2010 - link
tbh, I somewhat doubt it...jay401 - Tuesday, June 22, 2010 - link
iAds will probably be enough to keep me from getting the new iPhone to replace my current cell phone. i just don't trust Apple with that sort of power over my user experience.i dont want ads interrupting and distracting me from my task. i want to get my chosen task done efficiently and quickly.
"If it wanted to Apple could even sell ads in books."
Yes, if Apple wanted customers to drive to Cupertino to punch the iAds team directly in the face.