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

[Nuno Santos]

Hummmm, if that is true than I'm probably again looking for an unknown issue.

The truth is that I don't have an iPad Air so I'm blind.

I have already identified some useless memory usages.

I found that rectangles and loaders can actually spend a lot of memory. If I can replace them for items it is better.

--
Nuno Santos

No dia 21/04/2015, às 12:58, Harri Pasanen <harri at mpaja.com> escreveu:

> 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
>> +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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> 
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