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 2013/9/21 Giuseppe D'Angelo <dange...@gmail.com> > On 21 September 2013 14:47, Etienne Sandré-Chardonnal > <etienne.san...@m4x.org> wrote: > > I'm experiencing this issue : a 64-bit int QMap slows my app comparing > to a > > 32-bit int one. I'm compiling with GCC-MinGW64, so a 64-bit compiler. > > Shouldn't it be as fast? The QMap is not very large (maybe 1000 elements) > > and I have much bigger structures in my app, so the memory size should > not > > be responsible for the slowdown. > > Do you have a SSCCE [1] that clearly shows the issue? > > [1] http://sscce.org/ > > -- > Giuseppe D'Angelo >
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