[Xcb] xlib versus xcb performance in Qt Applications?

Jamey Sharp jamey at minilop.net
Sat Mar 31 08:33:29 PDT 2012

On 3/31/12, Rick Stockton <rickstockton at reno-computerhelp.com> wrote:
> On 03/30/2012 07:39 PM, Jeremy Huddleston wrote:
>>  On Mar 30, 2012, at 5:41 PM, Rick
>> Stockton<rickstockton at reno-computerhelp.com>   wrote:
>>>  And BTW, we've removed xlib support in Qt5, switching to xcb on X11
>>> platforms. :)

I'm super excited to hear that. :-)

> So, what kinds of things would you like me to compare? I've got a
> example Apps with flying things; one which plays a short movie; and
> various other examples of "Painting Goodness". Can I assume that input
> (keyboard, mouse) doesn't need testing, because input events from xcb
> are 1:1 with events from Xlib? Or should I cover some input events too?

XCB has a 4kB receive buffer, but Xlib doesn't buffer input. So it's
possible that under very heavy event load, XCB might do better. My
guess is it won't make a measurable difference, but it would be
interesting to find out.

I look forward to seeing your results!

BTW, how did you guys handle keyboard input? We haven't provided very
good help for that yet, that I'm aware of.


More information about the Xcb mailing list