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From: Phillip Susi <>
To: Daniel Vetter <>
Cc: Geert Uytterhoeven <>,
	Linus Torvalds <>,
	Pavel Machek <>, Randy Dunlap <>,
	LKML <>,
	"linux-doc\" <>,
	Greg Kroah-Hartman <>,
	dri-devel <>,
	Linux Fbdev development list <>
Subject: Re: fbcon: remove soft scrollback code (missing Doc. patch)
Date: Tue, 02 Feb 2021 10:13:14 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <YBlfKgQ1laQLFqpW@phenom.ffwll.local>

Daniel Vetter writes:

> Just a quick comment on this: Since most framebuffers are write-combining,
> and reads from that tend to be ~3 orders of magnitude slower than writes
> (at least on the pile of machines I looked at here, there's big
> differences, and some special streaming cpu instructions to make the
> reading side not so slow).
> So scrolling by copying tends to be significantly slower than just
> redrawing everything.

I know this was the case years ago with AGP as iirc, it doubled ( 4x, 8x
) the PCI clock rate but only for writes wasn't it?  I thought this was
no longer an issue with PCIe, but if it is, then I guess I'll go ahead
with cleaning up the dead code and having it re-render with the larger
text buffer.

  reply	other threads:[~2021-02-02 15:24 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
     [not found] ` <>
     [not found]   ` <>
     [not found]     ` <>
2021-01-14 15:56       ` fbcon: remove soft scrollback code (missing Doc. patch) Geert Uytterhoeven
2021-01-14 16:11         ` Daniel Vetter
2021-01-15  8:06           ` Geert Uytterhoeven
2021-02-03  8:03             ` Thomas Zimmermann
2021-01-22 18:55         ` Phillip Susi
2021-01-25 15:39           ` Geert Uytterhoeven
2021-02-02 14:18           ` Daniel Vetter
2021-02-02 15:13             ` Phillip Susi [this message]
2021-02-02 15:23               ` Daniel Vetter

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