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Date:      Sat, 5 Mar 2011 13:17:18 +0000
From:      Alexander Best <arundel@freebsd.org>
To:        "illoai@gmail.com" <illoai@gmail.com>
Cc:        David Demelier <demelier.david@gmail.com>, freebsd-questions@freebsd.org
Subject:   Re: FreeBSD kernel init slower than linux
Message-ID:  <20110305131718.GA57122@freebsd.org>
In-Reply-To: <AANLkTimOnkSZZ_jgnxVPtLCqm=uQzoF_GKpReqsuvZ7w@mail.gmail.com>
References:  <4D716372.2050606@gmail.com> <AANLkTimOnkSZZ_jgnxVPtLCqm=uQzoF_GKpReqsuvZ7w@mail.gmail.com>

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On Fri Mar  4 11, illoai@gmail.com wrote:
> On 4 March 2011 17:10, David Demelier <demelier.david@gmail.com> wrote:
> > Hello,
> >
> > I know this is a awful subject, but I recently tried a Gentoo on my laptop
> > and I was surprised to see Linux booting about 2-3 times faster than
> > FreeBSD.
> >
> > I don't talk about the init/rc script but only kernel initialisation. For
> > linux kernel it's around 5-6 seconds vs 15-18 seconds for FreeBSD.
> >
> > Why FreeBSD is so slower than Linux to boot the kernel?
> >
> 
> USB probe times for FreeBSD are extremely
> long.  I'm not sure of Linux parallelizes this
> or just waits until rc time.
> 
> Wireless seems to be a similar issue here.

also timeouts in freebsd were chosen very conservatively. you might want to
alter those. examples are ATA or CAM timeouts.

also there seem to be a number of hardcoded delays present in some code which
have to be altered in the source tree. an example is the folowing code in the
boot stage 2 (boot2, but also present in gptboot and the zfs counterparts):

if (autoboot && keyhit(3)) {

cheers.
alex

> 
> -- 
> --

-- 
a13x



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