Re: textdumps are too slow

> 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.org