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Memory allocation testing between two devices

Answer 1

+4 A:

I am not sure if I understand this correctly, but the figures on the last row (7.6/5 GB) refer to available flash memory, not to the RAM. Therefore they say nothing about the expected performance of a memory-intensive application. Neither the amount of free RAM is exactly telling, because the system will start killing large applications when the memory is scarce and the amount of free memory will go up.

zoul 2010-03-02 05:14:58

I supposed that RAM in all iPhone 3G's is 128MB(3GS 256MB). So I ruled that out as a factor.There is no multitasking in iphone, I guess. So if the iPhone is running only one application, why should the performance be different in two devices of the same RAM?

erastusnjuki 2010-03-02 05:36:50

Yes. The figures in the last row represent hard-drive memory. Is there any way to check RAM?

erastusnjuki 2010-03-02 05:40:03

Yes, Instruments is your friend. See Run → Run With Performance Tool → Object Allocations and others. There is also a Leaks instrument that can help you find the leaks.

zoul 2010-03-02 05:42:57

There is multitasking on iPhone, you just are not allowed to use it. There are many processes running all the time, possibly including the factory Mail.app, Safari, iPod and others. The actual amount of free memory can differ between devices of the same type and configuration.

zoul 2010-03-02 05:45:30

Instruments doesn't show me total RAM memory capacity it shows percentages. Is that what can help me see whether the RAM between the two devices is different?

erastusnjuki 2010-03-02 06:05:43

any references on the multitasking point?

erastusnjuki 2010-03-02 06:06:30

The multitasking point can be easily seen in the process list in Instruments. There are quite a few processes running along with your app. The amount of free RAM is always different on two different devices – it depends on the pages you have displayed in Safari and many other things. You could probably eliminate this difference by restarting the device.

zoul 2010-03-02 06:52:00

If you use the Memory Monitor instrument in Instruments, you will get an exact readout of the memory usage of your application, as well as all other processes on the device.

Brad Larson 2010-03-03 18:10:24

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Memory allocation testing between two devices

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