Date: Fri, 7 Apr 2023 15:07:13 -0700 (PDT) From: "Rodney W. Grimes" <freebsd-rwg@gndrsh.dnsmgr.net> To: Alan Somers <asomers@FreeBSD.org> Cc: Warner Losh <imp@bsdimp.com>, Poul-Henning Kamp <phk@phk.freebsd.dk>, FreeBSD CURRENT <freebsd-current@FreeBSD.org> Subject: Re: textdumps are too slow Message-ID: <202304072207.337M7Dim016129@gndrsh.dnsmgr.net> In-Reply-To: <CAOtMX2gbpy4AXXScbEsc5ho3cv7M%2BT8aVuwyak-PeSdzPqOd_g@mail.gmail.com>
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> On Fri, Apr 7, 2023 at 12:08?PM Warner Losh <imp@bsdimp.com> wrote: > > > > > > > > On Fri, Apr 7, 2023 at 6:20?AM Poul-Henning Kamp <phk@phk.freebsd.dk> wrote: > >> > >> -------- > >> Alan Somers writes: > >> > On Fri, Apr 7, 2023 at 2:22=E2=80=AFAM Poul-Henning Kamp <phk@phk.freebsd.dk> wrote: > >> > >> > > I would expect them to be limited by the serial console speed before > >> > > the video system speed ? > >> > > >> > That was my first guess, too. But my serial console is 115200 baud, > >> > which is faster than the low performance server grade video card. > >> > >> Ok, that must truly be sucky hardware... > > > > > > That's 10x slower than 1990s era VGA cards then... 115200 is 11k characters a second, > > and FreeBSD on 1990s era VGA cards was in excess of 1MB/s, faster if not a pure ISA > > card... Video hardware that's slower than *THAT* likely indicates a big big problem in > > our video stack. > > > > Warner > > While I'm logged into the video terminal in a normal login session, I > measure about 28M characters/second. So maybe the slow speed is due > to something inefficient in ddb(4). Do you mean to a physically connected vga display and usb/ps2 connected keyboard, or do you mean a serially connected video terminal, or something else like a console created by a BMC? One other thing that could be at issue is a console redirection via serial port, that can make "VGA device" performance appear abismal. -- Rod Grimes rgrimes@freebsd.orghelp
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