simple task to speed up booting

[Poul-Henning Kamp]

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In message <1419224743.1018.108.camel at freebsd.org>, Ian Lepore writes:

>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 investigated this a bit today.  I instrumented the loader on arm to
>count how many times twiddle() is called while loading a 5.5MB kernel.
>When loading over NFS it was called 5580 times.  When loading from an
>sdcard it was called 284 times.

It would be plenty if it twiddled once per second, in fact it would
probably be much better if it *only* twiddled once per second, because
the at least people could count the steps and gain some idea where
in the process the problem is.

>So all in all it seems like different kinds of IO need different
>throttling, something like the attached (which also still has some stats
>output in it).  I can't decide if it's worth committing... it'll have a
>lot of value to someone with slow serial and netbooting, is that common?

How about a compile time "global" divisor so people can reduce it
even further ?

But even without that: Please commit

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.