Re: textdumps are too slow

On Fri, Apr 7, 2023, 4:07 PM Rodney W. Grimes <freebsd-rwg@gndrsh.dnsmgr.net>
wrote:

> > 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


It's a BMC video console.  I'm also using a BMC serial port, but during
panic I measured the serial port as faster than the video port.


>