Anand - I enjoy your site and it's disappointing to see you continuing to support this misinformation:
"lack of true multitasking on iOS"
iOS implements "true" preemptive multitasking but it is tightly controlled for arguably good reasons. It isn't a cooperative "task switcher" like MacOS 7.
I expected Anandtech would be a bit more technical and a bit more accurate than this.
The argument isn't that it's not preemptive, but rather most of what you're not using is kept out of memory (as you pointed out, for good reasons). The point is simply that a doubling of DRAM size won't necessarily improve performance in existing workloads as a result since memory management is pretty strict already.
It doesn't have true multitasking. Yes, the underlying OS does, but it's not actually exposed to the users or third parties, so practically speaking it does not.
I've heard of both 32nm processes and 28nm processes, but not anything at 38nm. Really, I'm just comparing it to "28/32nm A5" earlier in the sentence. I don't have the technical knowledge to say that it is incorrect.
From what I understand, Apple maintaining 512MB of RAM has much to do with battery life. An increase in RAM would likely draw more power. Wouldn't you agree?
That is also true, Brian and I were having the same discussion there - without conservatively managing apps in memory, more memory would simply allow more data to be resident in memory, which results in more frequent cell refreshes and could impact battery life. I suspect the move to a smaller process node will help give Apple the breathing room it needs to accommodate more data in memory with a negligible impact on battery life.
I find the argument of having more RAM sucking up power to be silly, otherwise, it wouldn't have made sense for the iPhone 4 to have 512MB of RAM when all other A4 class devices have 256MB.
And what's even weirder is that everyone seems to be ignoring that "less RAM = having to refetch data over 3G radio". Or the fact that kicking apps out of memory means they have to be re-initialized again, burning CPU cycles. I don't know about you, but I think that's a much more costly process in terms of battery life.
None of this really applies to desktop operating systems because they have virtual memory, nor are they really aware of battery life constraints. If the system is under memory pressure, it'll just dump data to the disk and call it back up when it needs to. All mobile OS avoid this costly procedure because it's extremely costly to write just a few bits of data to Flash memory as entire pages have to be erased first.
Regardless, the most likely real reason Apple didn't include 1GB of RAM is to a) save costs and b) they don't feel like they need more. The OS clearly runs very well compared to the competition due to not having to worry about garbage collection and every OS developer being very aware of the amount of RAM used (use too much and your app gets killed).
iPhone 4 did need the extra memory and was the first of their phone-devices that had memory in PoP configuration to begin with. Radio is in it's own basebandchip with it's own RAM so I'm not sure what your trying to get at. You don't need a 512MB cache for the radio. Having less RAM does mean about half the power usage in this case. With regard to just the ram. Not that the iPad 2 had 1GB. It's really just the same chip as in iPad 2 with production sorted out under the iPad 2-run and binned for the phones. Otherwise probably no alterations.
Background apps does mean more then DRAM-usage they are usually terrible when it comes to using the network and cpu just see the Skype app on Android etc. You definitively needs to put apps to sleep or suspend to flash when it comes to power otherwise the phone would quickly be busy doing things it doesn't need to do. But remember the iPhone 4 not only competed against an run more larger apps but also introduced third party multitasking/background apps. Upping the ram was only sensible then. Neither was power the same concern as now, when dualcore and new baseband meant it wasn't getting better in terms of batterylife.
Android devices with only 512MB RAM aren't known for their superior battery life over 768MB and 1GB counterparts. I believe they did it mainly to save costs, knowing that the iPhone 4S would sell well anyway. Just like the iPod Touch and the iPad1 which both only had 256MB.
What are quad cores going to be used for exactly in a tablet or smartphone? Even computer applications are slow to really optimized from dual core to quad cores. Many things on a tablet or smartphone are already hardware accelerated with dedicated chips such as audio and video encoding and decoding. There are dedicated image signal processors for the cameras. Other tasks could potentially run faster on the GPU once Apple implements OpenCL.
And if Apple does switch to dual core ARM Cortex A15, which I think is realistically too early for the iPad 3, performance relative to a quad core Cortex A9 won't be a huge concern.
The key here is "clocked" not measured performance as the case we saw in Anand's benchmarks the Tegra 2 was embarrassed even single core A8 SOC had best it in some areas which should never have happened.
Of course Android fans like to buy big numbers instead of actually comparing actual benchmark results to gauge true performance.
The SSGS2 being higher clocked than IP4S but fails to beat it across the board is a shining example of this.
Why shouldn't at least a 32nm Cortex-A15 dual-core be possible in the March/April time frame for the iPad 3? With the A4 and A5 Apple was among the first offering new architectures in widely available mass market consumer products. Especially the A5 broke new ground with the SGX543MP2 (plus some other goodies) and a die size that AFAIK almost no one saw coming.
Well, Apple made two Cortex A8 CPUs (65nm in 3GS and 45nm in iPhone4) so I suspect they will again make two iterations of A9. It's a lot like intel tik-toc strategy. A die shrink, then a new architecture on the same process.
A welcome large step for the iPad 3 on top of not just expectedly faster hardware, would be a doubling of PPI @ 2048x1536 to make pixelation at the current screen dimensions a non issue.
Anand, are you and Brian planning a full on review of the 4s like you guys did with the 4? Yours was the best and more informative review on the internet. I hope you do.
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34 Comments
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eliotw - Thursday, October 13, 2011 - link
Anand - I enjoy your site and it's disappointing to see you continuing to support this misinformation:"lack of true multitasking on iOS"
iOS implements "true" preemptive multitasking but it is tightly controlled for arguably good reasons. It isn't a cooperative "task switcher" like MacOS 7.
I expected Anandtech would be a bit more technical and a bit more accurate than this.
E
Anand Lal Shimpi - Thursday, October 13, 2011 - link
The argument isn't that it's not preemptive, but rather most of what you're not using is kept out of memory (as you pointed out, for good reasons). The point is simply that a doubling of DRAM size won't necessarily improve performance in existing workloads as a result since memory management is pretty strict already.Take care,
Anand
Anand Lal Shimpi - Thursday, October 13, 2011 - link
Clarified a bit, hopefully that makes it better :)Take care,
Anand
eliotw - Thursday, October 13, 2011 - link
Thanks I think that's much better.Wolfpup - Friday, October 14, 2011 - link
It doesn't have true multitasking. Yes, the underlying OS does, but it's not actually exposed to the users or third parties, so practically speaking it does not.Wolfpup - Friday, October 14, 2011 - link
For that matter, PalmOS 5 a decade ago actually had real multitasking. It was cooperative, but did work, and was available to any developer.headbox - Sunday, October 16, 2011 - link
Yeah, and when you use an iPhone you're always thinking "oh damn, I wish this was as awesome as PalmOS 5" :rolleyesImSpartacus - Thursday, October 13, 2011 - link
Is "28/38nm A6" a typo?I've heard of both 32nm processes and 28nm processes, but not anything at 38nm. Really, I'm just comparing it to "28/32nm A5" earlier in the sentence. I don't have the technical knowledge to say that it is incorrect.
Anand Lal Shimpi - Thursday, October 13, 2011 - link
Fixed :)madoublet - Thursday, October 13, 2011 - link
From what I understand, Apple maintaining 512MB of RAM has much to do with battery life. An increase in RAM would likely draw more power. Wouldn't you agree?Anand Lal Shimpi - Thursday, October 13, 2011 - link
That is also true, Brian and I were having the same discussion there - without conservatively managing apps in memory, more memory would simply allow more data to be resident in memory, which results in more frequent cell refreshes and could impact battery life. I suspect the move to a smaller process node will help give Apple the breathing room it needs to accommodate more data in memory with a negligible impact on battery life.Take care,
Anand
dagamer34 - Thursday, October 13, 2011 - link
I find the argument of having more RAM sucking up power to be silly, otherwise, it wouldn't have made sense for the iPhone 4 to have 512MB of RAM when all other A4 class devices have 256MB.And what's even weirder is that everyone seems to be ignoring that "less RAM = having to refetch data over 3G radio". Or the fact that kicking apps out of memory means they have to be re-initialized again, burning CPU cycles. I don't know about you, but I think that's a much more costly process in terms of battery life.
None of this really applies to desktop operating systems because they have virtual memory, nor are they really aware of battery life constraints. If the system is under memory pressure, it'll just dump data to the disk and call it back up when it needs to. All mobile OS avoid this costly procedure because it's extremely costly to write just a few bits of data to Flash memory as entire pages have to be erased first.
Regardless, the most likely real reason Apple didn't include 1GB of RAM is to a) save costs and b) they don't feel like they need more. The OS clearly runs very well compared to the competition due to not having to worry about garbage collection and every OS developer being very aware of the amount of RAM used (use too much and your app gets killed).
Penti - Thursday, October 13, 2011 - link
iPhone 4 did need the extra memory and was the first of their phone-devices that had memory in PoP configuration to begin with. Radio is in it's own basebandchip with it's own RAM so I'm not sure what your trying to get at. You don't need a 512MB cache for the radio. Having less RAM does mean about half the power usage in this case. With regard to just the ram. Not that the iPad 2 had 1GB. It's really just the same chip as in iPad 2 with production sorted out under the iPad 2-run and binned for the phones. Otherwise probably no alterations.Background apps does mean more then DRAM-usage they are usually terrible when it comes to using the network and cpu just see the Skype app on Android etc. You definitively needs to put apps to sleep or suspend to flash when it comes to power otherwise the phone would quickly be busy doing things it doesn't need to do. But remember the iPhone 4 not only competed against an run more larger apps but also introduced third party multitasking/background apps. Upping the ram was only sensible then. Neither was power the same concern as now, when dualcore and new baseband meant it wasn't getting better in terms of batterylife.
quiksilvr - Thursday, October 13, 2011 - link
If it is two 512MB chips and not just one, 1 GB chip, then yes.zorxd - Thursday, October 13, 2011 - link
Android devices with only 512MB RAM aren't known for their superior battery life over 768MB and 1GB counterparts.I believe they did it mainly to save costs, knowing that the iPhone 4S would sell well anyway.
Just like the iPod Touch and the iPad1 which both only had 256MB.
MySchizoBuddy - Thursday, October 13, 2011 - link
Nvidia coming up with quad core this year. Can Apple afford to stay in the dual core world for iPad 3?ltcommanderdata - Thursday, October 13, 2011 - link
What are quad cores going to be used for exactly in a tablet or smartphone? Even computer applications are slow to really optimized from dual core to quad cores. Many things on a tablet or smartphone are already hardware accelerated with dedicated chips such as audio and video encoding and decoding. There are dedicated image signal processors for the cameras. Other tasks could potentially run faster on the GPU once Apple implements OpenCL.And if Apple does switch to dual core ARM Cortex A15, which I think is realistically too early for the iPad 3, performance relative to a quad core Cortex A9 won't be a huge concern.
michael2k - Thursday, October 13, 2011 - link
The A5 is anywhere from 2 to 6 times faster (GPU, some CPU) than a Tegra 2.Can Nvidia afford to NOT go quad core this year?
Apple's A5 is likely to be nearly identical to a quad core Tegra 3, from a performance standpoint, with a die shrink+clock boost.
zorxd - Friday, October 14, 2011 - link
the Tegra 2 CPU is slightly slower clock per clock. But never 2x. Also, Tegra 2 is clocked 25% faster than A5 in iPhone 4S.vision33r - Friday, October 14, 2011 - link
The key here is "clocked" not measured performance as the case we saw in Anand's benchmarks the Tegra 2 was embarrassed even single core A8 SOC had best it in some areas which should never have happened.Of course Android fans like to buy big numbers instead of actually comparing actual benchmark results to gauge true performance.
The SSGS2 being higher clocked than IP4S but fails to beat it across the board is a shining example of this.
zorxd - Monday, October 17, 2011 - link
Some benchmarks are GPU-dependant. Other are OS-dependent, so we must be careful.Show me a single CPU-dependant benchmark where a 1GHz Tegra2 is 2x slower than a 800 MHz A5.
lurker22 - Thursday, October 13, 2011 - link
Any word on SVDO support in the qualcom chip?Cr0nJ0b - Thursday, October 13, 2011 - link
I've been wondering the same thing, what is up with this?Mike1111 - Thursday, October 13, 2011 - link
Why shouldn't at least a 32nm Cortex-A15 dual-core be possible in the March/April time frame for the iPad 3? With the A4 and A5 Apple was among the first offering new architectures in widely available mass market consumer products. Especially the A5 broke new ground with the SGX543MP2 (plus some other goodies) and a die size that AFAIK almost no one saw coming.zorxd - Thursday, October 13, 2011 - link
Well, Apple made two Cortex A8 CPUs (65nm in 3GS and 45nm in iPhone4) so I suspect they will again make two iterations of A9.It's a lot like intel tik-toc strategy. A die shrink, then a new architecture on the same process.
But we will see.
introiboad - Thursday, October 13, 2011 - link
The teardown shows no sign of the usual Broadcom Wifi+Bluetooth IC. Have they integrated the base bands for those in the A5??Eldia - Monday, October 17, 2011 - link
Confirmed that the BCM4330 is used.http://www.ubmtechinsights.com/teardowns/apple-iph...
dagamer34 - Thursday, October 13, 2011 - link
Any power saved from having less RAM is instantly lost from having to turn on the 3G radio again to refetch data.Penti - Thursday, October 13, 2011 - link
Having less ram doesn't mean having no cache in the browser and doesn't mean it need to receive every bit of data twice.choirbass - Friday, October 14, 2011 - link
A welcome large step for the iPad 3 on top of not just expectedly faster hardware, would be a doubling of PPI @ 2048x1536 to make pixelation at the current screen dimensions a non issue.choirbass - Friday, October 14, 2011 - link
on second thought, youd still have some noticeable pixelation by only doubling it, but it would be at least an improvement in any case.choirbass - Friday, October 14, 2011 - link
hm,. ok, yeah... ~2560x2048 is about whats necessary @ 9.7" to be near 330ppi (its a couple pixels above). not sure thats gonna happen, lol :P00DC2TW - Friday, October 14, 2011 - link
Anyone know if the MDM6610 will support tmobile 3G USA?Dennis Travis - Sunday, October 16, 2011 - link
Anand, are you and Brian planning a full on review of the 4s like you guys did with the 4? Yours was the best and more informative review on the internet. I hope you do.