should we use QT_NO_GLIB=1 like kwin?

[Matt Rogers]

On Wed, Oct 6, 2010 at 5:07 PM, Milian Wolff <mail at milianw.de> wrote:
> On Wednesday 06 October 2010 23:03:30 Aleix Pol wrote:
>> On Wed, Oct 6, 2010 at 10:51 PM, Milian Wolff <mail at milianw.de> wrote:
>> > Hey all,
>> >
>> > since I spent some time today to investigate the excessive wakeups of
>> > KDevelop
>> > while it's supposedly doing *nothing* I got a suggestion by pinotree in
>> > #kde-devel:
>> >
>> > He proposed to use QT_NO_GLIB for KDevelop. Indeed that removes most
>> > calls to
>> > poll() when comparing a strace -tt -p $(pidof kdevelop).
>> >
>> > See e.g. here how to implement:
>> >
>> >
>> > http://websvn.kde.org/trunk/KDE/kdebase/workspace/kwin/main.cpp?revision=
>> > 1177865&view=markup search for QT_NO_GLIB.
>> >
>> > It's very easy and for kwin it also fixed high CPU usage bugs. Didn't we
>> > have
>> > some like these as well?
>> >
>> > Anyhow, the draw back would be: It's not possible to use gstreamer or
>> > phonon
>> > in KDevelop anymore as these require that glib eventloop. I personally
>> > don't
>> > see a reason (now) for using phonon in KDevelop. In the far future one
>> > might
>> > want to play screencasts or other media in embedded documentation...
>> >
>> > So what do you guys think: Should we try it out? Or leave it as-is?
>> >
>> > Bye
>
>> As I said on the IRC I wouldn't be against it but I'd like to make it sure
>> that we _need_ that to work properly. Isn't there a reason for these poll
>> calls for instance? If you open a small app and leave it open it doesn't
>> take CPU constantly, at least...
>
> Ah indeed, I didn't make that clear in my first mail:
>
> 1) according to powertop the wakeups are not noticeably less with QT_NO_GLIB
> 2) there are still quite a few stats etc. going on according to strace which
> I'll investigate sooner or later.
>
> It's just that pinotree (someone whom I trust code-wise) suggested it and that
> kwin already uses it... I hoped for a freebee...
> --
> Milian Wolff
> mail at milianw.de
> http://milianw.de
>

If the wakeups aren't noticeably less, then I don't see a reason to set it.
--
Matt