[Xcb] XPutImage and context switches / roundtrips?

Julien Cristau jcristau at debian.org
Tue Sep 23 05:57:37 PDT 2008

On Thu, Sep 11, 2008 at 02:48:58 -0700, Barton C Massey wrote:

> In message <194f62550809101503x1db44cb3lbf1f0245a877b4a8 at mail.gmail.com> you wrote:
> > Well, compile-time would mean all applications would have
> > to use the fixed-size buffer, regardless wether they need
> > it or not.
> Yes.  All applications and clients of the library would have
> to agree on a buffer size for the platform.  On a modern
> platform, that can usually be pretty large without anyone
> caring.  I forget what the default Xlib buffer size is, but
> it's way bigger than 4K.

#define XLIBDEFAULTBUFSIZE 16384 /* 16k */

according to src/OpenDis.c here.

I believe the 4k buffer size in libxcb should be revisited.  Note that
in Xlib, the buffer size could be changed both at compile time by
redefining XLIBDEFAULTBUFSIZE and at runtime with the XLIBBUFFERSIZE
environment variable.  But really, 4k seems too small.


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