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Date:      Fri, 15 Aug 1997 17:01:21 -0500 (EST)
From:      "John S. Dyson" <toor@dyson.iquest.net>
To:        psd@worldaccess.nl (Paul Dekkers)
Cc:        shawn@luke.cpl.net, jdn@qiv.com, freebsd-questions@FreeBSD.ORG
Subject:   Re: FreeBSD is slower than Linux !?
Message-ID:  <199708152201.RAA00904@dyson.iquest.net>
In-Reply-To: <Pine.LNX.3.96.970814222053.136C-100000@gromit.nev.ml.org> from Paul Dekkers at "Aug 14, 97 10:23:19 pm"

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> On Wed, 13 Aug 1997, Shawn Ramsey wrote:
> 
> >Do be fair, I think you should mount the FreeBSd disks asyncronously. By
> >default, it is set to Synchronously. Linux, at least it used to be this
> >way, is mounted asynch. Disk access is HUGELY increases under FreeBSD if
> >it is set to asynch. (mount -o async /dev/filesystem)
> 
> Joking? Look at my dd-test:
> 	Linux	fBSD	fBSD with async	(linux with sync)
> dd-test	2.61	4.95	4.78		2m06 (!!)
> also with the other tests fBSD is still slower and the sync is faster,
> even faster than last time without async, so FreeBSD really wrote
> everything already.
> and I'm sure the / was mounted with async! (checked with mount)
> i'm using an i486 with 40mb's of memory so that should be enough for
> FreeBSD to do something :-)
> 
> -= Paul =-
> 
> P.S. ext2 with sync mounted is terribly slow! Comparing that with fbsd, fbsd
> is faster in writing really to disk.
> 

With the -async option, FreeBSD actually writes long sequential writes without
blocking.  Those writes are done that way so that the disk-cache doesn't get
backlogged with lots of dirty pages (buffers.)  I have been pondering a really
async option, but that would not be the default async.  Our async option is
really an async metadata option.

John



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