[Mesa-dev] [PATCH 17/19] glx: Replace DRI2SwapBuffers() custom protocol with XCB.

[Chad Versace]

> +       swap_buffers_cookie =
> +          xcb_dri2_swap_buffers_unchecked(c, pdraw->xDrawable,
> +                                          target_msc_hi, target_msc_lo,
> +                                          divisor_hi, divisor_lo,
> +                                          remainder_hi, remainder_lo);
> +       /* Immediately wait on the swapbuffers reply.  If we didn't, we'd have
> +        * to do so some time before reusing a (non-pageflipped) backbuffer.
> +        * Otherwise, the new rendering could get ahead of the X Server's
> +        * dispatch of the swapbuffer and you'd display garbage.
> +        *
> +        * We use XSync() first to reap the invalidate events through the event
> +        * filter, to ensure that the next drawing doesn't use an invalidated
> +        * buffer.
> +        */
> +       XSync(pdraw->psc->dpy, False);
> +       swap_buffers_reply =
> +          xcb_dri2_swap_buffers_reply(c, swap_buffers_cookie, NULL);
> +       ret = merge_counter(swap_buffers_reply->swap_hi,
> +                           swap_buffers_reply->swap_lo);
> +       free(swap_buffers_reply);

Will this sync harm performance for artificial benchmarks? I'm asking because
this hunk reminds me of Oliver's comments that Dante was slower on EGL than GLX
perhaps due to extra X roundtrips.

Anyway, roll-our-own-X-protocol needs to die.
Reviewed-by: Chad Versace <chad.versace at linux.intel.com>