[Interest] Question to members of the Qt team: why does an empty project consumes so much memory on iOS?
Nuno Santos
nunosantos at imaginando.pt
Tue Apr 21 14:16:28 CEST 2015
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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