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    SubjectRe: xterm scrolling speed - scheduling weirdness in 2.6 ?!
    On Sun, 4 Jan 2004 14:32, Tim Connors wrote:
    > > Not quite. The scheduler retains high priority for X for longer so it's
    > > no new dynamic adjustment of any sort, just better cpu usage by X (which
    > > is why it's smoother now at nice 0 than previously).
    > >
    > > > If either the scheduler or xterm was a bit smarter or
    > > > used different thresholds, the problem would go away. It would also
    > > > explain why there are people who cannot reproduce it. Perhaps a
    > > > somewhat faster or slower system makes the problem go away. Honnestly,
    > > > it's the first time that I notice that my xterms are jump-scrolling, it
    > > > was so much fluid anyway.
    > >
    > > Very thorough but not a scheduler problem as far as I'm concerned. Can
    > > you not disable smooth scrolling and force jump scrolling?
    > AFAIK the definition of jump scrolling is that if xterm is falling
    > behind, it jumps. Jump scrolling is enabled by default.
    > What this slowness means is that xterm is getting CPU at just the
    > right moments that it isn't falling behind, so it doesn't jump - which
    > means X gets all the CPU to redraw, which means your ls/dmesg anything
    > else that reads from disk[1] doesn't get any CPU.
    > Xterm is already functioning as designed - you can't force jump
    > scrolling to jump more - it is at the mercy of how it gets
    > scheduled. If there is nothing more in the pipe to draw, it has to
    > draw.
    > These bloody interactive changes to make X more responsive are at the
    > expense of anything that does *real* work.

    Harsh words considering it is the timing sensitive nature of xterm that relies
    on X running out of steam in the old scheduler design to appear smooth.


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