Intel845 IGP and XGetImage

[Austin Yuan]

On 4/21/05, Austin Yuan <yuanshengquan at gmail.com> wrote:
> I found a thread which addressed the same issue I mentioned in xorg
> lists. It is "X[Shm]GetImage is slow; what can I do about this? " .
> Now the problem seems on software memory copy from framebuffer to
> system memory. I will try shadowfb and compare the result with the
> normal case.
> Thanks!
> Austin Yuan
> 

Because Intel845 hasn't shadowfb support, I have tried
vesa-shadowfb,the result is:
                  intel845 driver               vesa                  
 vesa-shadowfb
XGetImage       380626                    181632                  73701
XPutImage         35227                      43300                  63153
It seems shadowfb has some improvement for XGetImage.         

> On 4/21/05, Austin Yuan <yuanshengquan at gmail.com> wrote:
> >   I am working on a project that transfers x window desktop from one
> > machine to another machine on intel845 platform. The transfer includes
> > 3 operations: get the desktop image, pass it on network, and show the
> > image on another side. I use XGetImage/XPutImage to get and show the
> > image. Now the problem is that XGetImage takes more time than
> > XPutImage and becomes the bottleneck of the whole system(My simple
> > demo shows one XGetImage call takes 116498us,but XPutImage only
> > 7362us). I trace XGetImage implementation on the server side. It will
> > fall into XAAGetImage, and because intel845 IGP driver doesn't
> > implement ReadPixmap(I think it is bitblt from framebuffer to system
> > memory), It will fall back to software bitblt.
> >   My question is whether intel845 IGP supports bitblt from
> > framebuffer to system memory. If not, why does XGetImage takes more
> > time than XPutImage,and how to optimize it?
> >
> > Thanks!
> > Austin Yuan.
> >
>