When does the iPhone 4 A4 cpu run at 1ghz?

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Furion
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When does the iPhone 4 A4 cpu run at 1ghz?

Post by Furion »

Hello everyone.

Had a curious feeling and i was just wondering if any of you had any thoughts on this.

According to a few benchmarks I have been looking at and using my own experience I have seen that there are certain times when the performance results between the iPhone 4 and the iPad have been as near as makes no difference, identical. Which shouldnt be the case if the iPhone is running at a max of ~800+ mhz. Now we all know the A4 chip in the iPad is the same one in the iPhone 4. And since the iPhone has a clock speed that is variable and is dynamically clocked depending on system loads...When does the iPhone hit the 1ghz speed? Does it do it when running 3D games or any other tasks that would stress its systems?

Some of the benchmarks clearly show the iPad ahead by some margin due to its permanant 1ghz clock and in others (which arent cpu or gpu bound) they come out even...

So...

basically...

What would give the iPhone cause to run at 1ghz?

I will quote this sources of some of the info i have found in addition to my own...

http://www.fudzilla.com/reviews/item/19 ... ?showall=1


"Whatever its motives may be, Apple decided not to reveal the specifications of its A4 processor during the iPad’s announcement in January, and only revealed the name of the processor itself. Of course, little did the industry know that the company would implement the same processor in its fourth-generation smartphone. Now that the product has materialized and has sold over 1.7 million units within its first three days, we can confirm without question that the device sports the same ARM-based 45nm A4 1GHz chip used in the iPad. But rather than being clocked straight at 1GHz, the A4 processor in the iPhone 4 runs at a variable clockspeed, allowing it to vary in speed and adjust according to application demands. It features a maximum clock of 1GHz just like the iPad, but for most applications it will essentially mimic Intel’s SpeedStep platform by adjusting voltages and clock speeds according to the number of applications running to improve power consumption efficiency."



and...

http://www.everythingicafe.com/forum/th ... led.57950/



"After spending some time talking to the senior iphone tech about my replacement phone last night, he asked if there's any feature requests I had or anything else he could help me with. Firstly, I told him custom text tones and email tones, and 3g hotspot. But then I asked him what the clock speed of the A4 in the iPhone 4 actually was. Was it an 800mhz like speculated. He told me that it's actually a variable clock speed processor, allowing it to vary it's speed with usage, with a max clock of 1ghz just like in the iPad.

Now some of you might say that he was just BSing me, but he really knew his stuff about the iPhone and specifically the 4, so I believe him. Plus a variable clock speed makes sense, and also explains the battery life improvments we are seeing. Plus it seems like an Apple way of doing things. "

Sorry for the longwinded post...


Thoughts anyone?

(ps. I posted this on the apple support forums but they seem to be very apathetic about replying to posts)

:mrgreen:
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Re: When does the iPhone 4 A4 cpu run at 1ghz?

Post by Anakha56 »

No idea. This is one reason why I love Android so much because you could get things like SetCPU to monitor and log CPU speeds. Hell even the Android SDK allowed you to pull the correct logs. Found this paid app but whether or not it works with the iPhone 4 or not who knows.

http://itunes.apple.com/app/checkup/id301417772?mt=8

Then there is this:

http://www.appstore.ca/2010/11/update-s ... utilities/

Then there is a paid app:

http://powerapp.eu/en/apps/20-sysmoni.html

Maybe ryan or DJV will know of any more?
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Re: When does the iPhone 4 A4 cpu run at 1ghz?

Post by Hman »

If I'm not mistaken it's based on how much of the cpu is utilised. On my N900 (ARM A8) the cpu speed can be set according to a configuration script depending on the percentage of cpu usage.

On the N900 there's basically 4 levels: idle, medium, high and max. With QCPU I can control the max and idle values, the os handles the medium and high settings.

I've seen that under some games the device only reaches "high" clock levels even with 3d graphics while some 2d apps might push it to maximum. So it all depends on your apps and how well they run.
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Furion
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Re: When does the iPhone 4 A4 cpu run at 1ghz?

Post by Furion »

Anakha56 wrote:No idea. This is one reason why I love Android so much because you could get things like SetCPU to monitor and log CPU speeds. Hell even the Android SDK allowed you to pull the correct logs. Found this paid app but whether or not it works with the iPhone 4 or not who knows.

http://itunes.apple.com/app/checkup/id301417772?mt=8

Then there is this:

http://www.appstore.ca/2010/11/update-s ... utilities/

Then there is a paid app:

http://powerapp.eu/en/apps/20-sysmoni.html

Maybe ryan or DJV will know of any more?
Thanks Anakha! Will check those apps out and see what i can find. I especially would like the idea of getting the cpu load logs to see. So im looking on both cydia and the links you have suggested
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Furion
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Re: When does the iPhone 4 A4 cpu run at 1ghz?

Post by Furion »

Hman wrote:If I'm not mistaken it's based on how much of the cpu is utilised. On my N900 (ARM A8) the cpu speed can be set according to a configuration script depending on the percentage of cpu usage.

On the N900 there's basically 4 levels: idle, medium, high and max. With QCPU I can control the max and idle values, the os handles the medium and high settings.

I've seen that under some games the device only reaches "high" clock levels even with 3d graphics while some 2d apps might push it to maximum. So it all depends on your apps and how well they run.

I think you might have a point here.

Consider this...When you are running a 3D game on your pc, speed is crucial however the cpu doesnt run at Max utilization (unless its a really old and slow processor or you are running multiple threads from different tasks) so the cpu doesnt really need to flex its muscle that much. its the GPU which is taking the hit. however that would be a different story if you are video encoding as an example.

I would suspect then that the iPhone would kick up its processor speed to the "max" setting that you are referring to if you use it for video recording at 720p or video playback at 720p. but i suspect this might be more GPU bound as the SGX unit does support hardware decoding for various codecs.

So now the key would be to figure out which apps stress the iphone to the point of doing this...

Perhaps then see what settings the app is triggering so that we might be able to make a app which acts a "NOS boost" where you want the full 1ghz speed on demand for a few moments before switching it off and allowing it to dynamically scale as usual...

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Re: When does the iPhone 4 A4 cpu run at 1ghz?

Post by Hman »

Well iOS is unix based so there should be a config file somewhere in there.....

I know on the N900 you can disable the scaling but I've never tried it. The device already drains the battery fairly quickly during normal usage at work.
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Re: When does the iPhone 4 A4 cpu run at 1ghz?

Post by Hman »

BTW: There's a nice program on my phone which let's me choose between different profiles. The one I'm using now sets the min speed to 500 and max to 850.

Here's a screenshot of it idling at 500Mhz

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Furion
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Re: When does the iPhone 4 A4 cpu run at 1ghz?

Post by Furion »

My hunt is turning up hopeless...

More power to you and Linux Hman

:(
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