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

[Harri Pasanen]

I referred to used memory figures.

For the same device, real vs. simulated, the simulator shows 2-2.5 times 
bigger memory consumption, with the sample size of 2 apps I tried with.

If you suspect images are what is using the memory, you can limit that 
by dropping to C++ and using QQuickImageProvider to serve the images on 
demand.

Harri

On 21/04/2015 13:43, Nuno Santos wrote:
> 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 <http://www.imaginando.pt>
> +351 91 621 69 62
>
>> On 21 Apr 2015, at 12:36, Harri Pasanen <harri at mpaja.com 
>> <mailto: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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