[Interest] QMap<int64_t> significantly slower than QMap<int32_t>

[Konstantin Tokarev]

22.09.2013, 13:24, "Etienne Sandré-Chardonnal" <etienne.sandre at m4x.org>:
> I don't, I have very only strong conviction from tests on a big large program. I was hoping that someone had an idea about the cause... Would this help to make one?
> I did a quick test : inserting 10000000 items in a QMap<int32_t, int> and QMap<int64_t, int> using rand() for key and value, measuring the delay with QDateTime::currentMsecsSinceEpoch.
> The int32 version took about 2100ms while the int64 took about 2300ms.
>
> So maybe this is only a memory cache issue. The difference is higher in my app (measured with a profiler), maybe because it decreases cache efficiency of other code parts.
>
> Using gcc 4.8.0 mingw64 rubenvb build, with Qt 4.8.1
> Etienne
>

Now try std::map<int32_t, int> and std::map<int64_t, int> - red-black tree should work faster than QMap's skiplist.


-- 
Regards,
Konstantin