2012/9/24 K. Frank <[email protected]>
> Hello Ruben!
>
> On Mon, Sep 24, 2012 at 8:11 AM, Ruben Van Boxem
> <[email protected]> wrote:
> > Hi everyone,
> >
> > I started investigating my gdb build's slowness.
> > ...
> > When I do
> > gdb testapp
> > set verbose on
> > run
> >
> > I see that the extra time is spent in the "Loading Symbols from"
> > QtCore4d.dll (2 vs 6 seconds) and QtGui4d.dll (6 vs 18 seconds). This is
> my
> > visual perception only.
>
> Thanks for the suggestion of running "set verbose on". Here's my
> data point for a very simple gui app that displays a sqlite table:
>
> QtCored4.dll: 0:19 (time "Reading symbols from")
> QtGuid4.dll: 1:28 (time "Reading symbols from")
> other: 0:01 (maybe mostly QtSqld4.dll / qsqlited4.dll)
>
> total: 1:48 (total time from "run" to displaying the
> app)
>
> (Times are given as minutes:seconds, and are good to probably
> about a second.)
>
> So I see what Ruben sees (most of the time spent reading the
> symbols from the two big Qt dll's), except that the times I see
> are much longer -- three to four times as long.
>
> I am running on a two-core, 1.60 GHz, 64-bit windows 7 system.
> Task manager suggests that gdb is more or less saturating one
> of the cores. (So processor speed probably explains part of
> my difference with Ruben, but not all.)
>
> This is with:
>
> g++ (GCC) 4.7.0 20110829 (experimental)
> GNU gdb (GDB) 7.3.0.20110829-cvs
>
> from Ruben's build:
>
> x86_64-w64-mingw32-gcc-4.7.0-stdthread_rubenvb.7z
>
> Qt is 4.8.0-rc1, and both Qt and the test app were plain-vanilla
> builds using the above compiler.
>
That is indeed quite long, but the relative times look like what I see. I
suppose the 3.2 GHz quad vs 1.6GHz might explain the slowness. GDB was
never fast on Windows :P
> > I have now rebuilt gdb with "--disable-nls" and I believe this is the
> thing.
> > Don't ask me why this is. The startup time reduces from ~19 seconds to
> 6-7
> > seconds, which is the same as mingw-builds gdb.
>
> I don't really understand what compatibility requirements there are
> between g++ and gdb, but if you think that I could use your new
> gdb with my existing Qt / test app, I'd be happy to give it a try
> and report back timings. (I don't really want to rebuild Qt in order
> to perform the test.)
>
Not necessary. The fault lies (afaict) entirely with the native language
support option I built GDB with previously. Expect my next build to have
this fix. I could build a seperate GDB package, but only if someone really
really needs it.
Cheers,
Ruben
> > ...
> > Another mystery solved by your anonymous hero,
>
> Indeed. Truly an International Man of Mystery!
>
> > Ruben
>
> Thanks for looking into this.
>
>
> K. Frank
>
>
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