Hello Ruben!

On Wed, Nov 2, 2011 at 9:01 AM, Ruben Van Boxem
<[email protected]> wrote:
> 2011/11/2 Pau Garcia i Quiles <[email protected]>
>>
>> Hi,
>>
>> Ruben, do you know why gdb seems to be slow at the start of session?
>> It seems to be the only thing preventing Qt and Qt Creator from
>> adopting mingw-w64 as the official gcc toolchain on Windows and
>> supporting x64.
>
> I'm sure that's not the only thing preventing Nokia from switching to
> MinGW-w64... although this is the first I've heard of slow startup of gdb. I
> never use it (never seems to work quite the way I want it to, but that's me
> being debugger-incapable).

For what it's worth, I've noticed that your 64-bit gdb (from the 4.7.0
std::thread build) seems slower.

I have a moderately complex qt application.  The command:

   gdb myApp

starts right away, and gives me the gdb prompt, but then running
the gdb command:

   run

takes several minutes of gdb using the processor before myApp
starts up (and starts using the processor).

I don't have exact timings, but from recollection, earlier 32-bit gdb's
I used (I believe tdm's mingw 4.4.1 build) might have taken a few
tens of seconds to do the same thing.

> Could you give me a reproducible example (and a
> gdb which works without the slow startup)? Maybe I could see where the
> difference comes from (or at least ask around). Have you tried 32-bit vs
> 64-bit as well?

Well, I saw faster startups with the above-mentioned tdm version:

   g++ --version:   g++.exe (TDM-2 mingw32) 4.4.1
   gdb -- version:   GNU gdb (GDB) 7.1

I can get you further details on the exact version, if you care.

I haven't tried it specifically, but I would expect that any little qt gui test
application -- instantiate a QApplication and instantiate and show a
QWidget, for example -- would work as a "reproducible example."

I should emphasize that I changed several things at the same time.
It was a Ruben 4.7.0 std::thread 64-bit mingw-w64 / qt 4.8.0-rc1 /
qwt 6.0.1 port / rebuild of my application that experiences the slower
gdb startup.

> And thank you for promoting my builds :)

Oh, yes...  I've been promoting your builds over on the qt list, all right!
(Hee-hee...)

> It would indeed be awesome to have
> Qt switch to MinGW-w64. I've been making sure all of it keeps working (err..
> building) since 4.7. If anyone asks for help with anything build-related,
> feel free to redirect them to this list!
>
> Ruben
> ...

Again, thanks for all of your efforts.


K. Frank

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