Date: Sun, 14 Dec 2014 11:18:53 -0600 From: Mike Karels <mike@karels.net> To: Ian Lepore <ian@freebsd.org> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk>, current@freebsd.org Subject: Re: simple task to speed up booting Message-ID: <201412141718.sBEHIr8g078422@mail.karels.net> In-Reply-To: Your message of Sun, 14 Dec 2014 07:52:11 -0700. <1418568731.935.8.camel@freebsd.org>
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> > On Sun, 2014-12-14 at 10:32 +0000, Poul-Henning Kamp wrote:
> > The rotating swirlie ('-/|\') in the loader accounts for a surprisingly
> > large part of our boot time on systems with slow-ish serial consoles.
> >
> > I think right now it takes a step for each 512 byte read, reducing that
> > to once every 64kB or even 1MB would be an improvement with the kind of
> > kernel sizes we have today.
> >
> I experimented with that a while ago using the attached patch and was
> disappointed with the results. As I vaguely remember it, a divisor of 8
> looked fine, but had no significant speedup. With a divisor of 32 the
> difference was measureable (only like 1.5 seconds or so faster), but it
> gave the impression that something was wrong, and the overall perception
> was that it was slower rather than faster, despite what a stopwatch
> said.
> I was testing at 115kbps, maybe at 9600 it would be significant. I
> don't understand why anything these days is still defaulting to 9600.
> It's the 21st century, but we never got the George Jetson flying cars we
> were promised, and apparently we're never going to break loose from the
> standards set by accoustic-coupled modems.
AFAIK, accoustic-coupled modems topped out at 300 baud; that's the fastest
one I've used, anyway.
Defaults are hard to change, though.
Mike
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