[Xcb] icccm

Josh Triplett josh.trip at verizon.net
Sun Mar 20 12:30:45 PST 2005

Vincent Torri wrote:
> And for you information, i've finished xcb port of evas !
> evas xlib : 2.893 (173.6 fps)
> evas xcb  : 2.831 (169.9 fps)
> i think that my code is maybe not good enough. maybe i could optimize it.

Those speeds are nearly identical; assuming you did a direct port of
every Xlib call to a corresponding XCB call (or pair of calls), then
that sounds about right.  You don't really get any speed advantages
until you start taking advantage of XCB's features, such as sending a
batch of requests and then getting all the replies later.

> And as i think of it, here is a question : should i use XCBSync where
> there was a XSynch ? or xcb allows to not use it in some cases ?

XCB never *requires* a call to XCBSync.  All XCBSync does is make a
request that has a reply (GetInputFocus), then wait for the reply; the
semantics of the X protocol require all previous requests to be handled
before that reply is returned, causing a sync.  (The semantics are
slightly different than Xlib, since only void requests may be batched in
Xlib, whereas all requests may be batched in XCB.)  To the best of my
knowledge, doing a sync or not doing a sync will not affect the
correctness of your application.

- Josh Triplett
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