Re: fbcon slowness [was NTP on 2.4.2?]

From: Pavel Machek (pavel@suse.cz)
Date: Fri Mar 30 2001 - 19:53:42 EST

  • Next message: Manuel A. McLure: "RE: tulip (was RE: Kernel 2.4.3 fails to compile)"

    Hi!

    > > >Are you using fbcon? If so, and if it goes away after starting X, then it
    > > >is the "fbcon kills interrupt latency" problem.
    > >
    > > Ug!!! This is getting bad. Give me some time. I plan on releasing a new
    > > vesafb using MMX to help speed up the drawing routines. It will help alot
    > > with the latency issues. I also know using ARM assembly we can greatly
    > > reduce the latency issues.
    >
    > On console speedups: back in the old days, scrolling a subregion of the
    > text console to be _really_ slow on some machines. I am talking about
    > text mode now, not framebuffer mode. On some cards, text mode is
    > actually very very slow and the framebuffer is faster. It took *2
    > seconds* to scroll a 50 lines of text 50 times on my 200MHz PPro system
    > 4 years ago. So less "back one screen" took 2 seconds. And Emacs uses
    > "scroll region by N lines" a lot. In those days, "N lines" scrolls
    > actually did N x 1 line scrolls, so text mode was really a burden on
    > that machine. I took to using X, with a single screen size xterm to
    > present the illusion of console mode.
    >
    > Well, nowadays on my laptop we have the joy of the framebuffer console.
    > Nice penguin aside, it means I get a console on the full screen area.
    >
    > But it is nearly as slow at scrolling as my old 200MHz PPro.

    You have same toshiba satellite as me, right?

    > Probably the lack of hardware area copies has something to do with
    > this. However, who isn't familiar with xterm "jump scroll" mode?
    > That's nice and fast.
    >
    > Could such a thing be implemented in the console driver?

    I believe so. It would be simple: if there's too much activit, defer
    framebuffer updates and only update in-memory copy. Sync from time to
    time. I'd certainly like to see that.
                                                                    Pavel

    -- 
    The best software in life is free (not shareware)!		Pavel
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