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    SubjectRe: Announce: DinX windowing system 0.2.0
    On Mon, 27 Dec 1999, Alan Cox wrote:

    > > Right. Just to clarify, performance is currently horrible on PC hardware
    > > because we read (memmove) from the framebuffer a lot when dragging windows
    > > around. And it seems PC hardware does this really slowly.
    >
    > All normal graphics hardware has this property. You can't do posted reads
    > but you can do posted writes.

    We've just switched to redrawing by default, rather than memmoving.
    Things are much, much faster on PCs now. I'll post an announcement of
    a new version as soon as I can get it uploaded.

    > > Right. The idea is just to take clipping and blitting out of the server
    > > process and put them in the kernel, to avoid lots of context switches and
    > > big complex buffering code.
    >
    > If your gui system is doing batching of commands this makes no difference.
    > Its one of the things X11 showed that was quite suprising.

    My understanding is that's certainly true for performance, but not memory
    usage and code size/complexity. My board only has 2MB.

    I'm sure I'm making lots of mistakes that have been made before, but
    that's okay - I'm learning lots from doing it. This is a project I've
    wanted to do for ages, and I quit my job so I could spend time on it.
    And I really do think we can build something smaller, simpler and faster
    than nanogui. We'll see.

    > > each, so the complexity of the visible area goes on the stack. Now, how
    > > much stack space does the kernel have? :)
    >
    > Bang...

    Also fixed in the new version, the clipping algorithm now uses a stack
    structure allocated with kmalloc. Thanks to everyone who provided advice
    on this. I now understand very clearly why a dynamically growing stack
    area would make dealing with races awful tough. :)

    Cheers,

    - Ben.

    -------------------------------------------------------------------
    Ben Williamson benw@pobox.com http://www.pobox.com/~benw/



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