[Interest] Question to members of the Qt team: why does an empty project consumes so much memory on iOS?

[Nuno Santos]

Harri,

That doesn’t make sense. Simulator is just displaying the real resolution of the device. In retina case 2048x1536. Why would it display something 2.5 times bigger for no apparent reason.

I have an iPad 2 and my app was designed in a 1024x768 base. My tests on a real device were on this base. The app memory usage on this conditions on the iPad are about 50Mb.

When we go to retina display, the problem is that the display cache multiplies by 4 because the resolution has doubled in both axis. This leads to an increase in memory. This is my guess.

I also think that Qt is loading all the libs at once. I cannot explain such a big memory footprint for an empty app.

I would like some insights from Qt dev people. 

I have been analysing, code portion by code portion and I have already found out interesting things that I will share later.

Regards,

Nuno Santos
Founder / CEO / CTO
www.imaginando.pt
+351 91 621 69 62

> On 21 Apr 2015, at 12:36, Harri Pasanen <harri at mpaja.com> wrote:
> 
> On 21/04/2015 10:38, Nuno Santos wrote:
>> I have been comparing the memory usage by an empty iOS and an empty Qt 
>> project on iOS running on an iPad Air. It seems that this is not 
>> comparable. Please take a look to the following image. The iOS native 
>> project uses 16Mb of memory, while the Qt project needs almost 90Mb. 
>> It happens that if the memory limit with an empty project is almost 
>> next to the limit, how can a normal app run smoothly? I have made this 
>> test, after realising that my app was using 160Mb on the iPad Air 
>> simulator. This is huge!
>> 
> 
> Note that the simulator displays about 2.5 times bigger figures than an 
> actual device.
> 
> (Some if it has to do with architecture, Intel seems to need more memory 
> and space than arm).
> 
> Just my 2 cents,
> 
> Harri
> 
> 
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