linux-kernel - Re: fbcon: remove soft scrollback code (missing Doc. patch)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 02 Feb 2021 10:13:14 -0500
From:   Phillip Susi <phill@...susis.net>
To:     Daniel Vetter <daniel@...ll.ch>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Pavel Machek <pavel@....cz>,
        Randy Dunlap <rdunlap@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "linux-doc\@vger.kernel.org" <linux-doc@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>
Subject: Re: fbcon: remove soft scrollback code (missing Doc. patch)


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.