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Date:      Fri, 22 Oct 2004 15:29:42 +0200
From:      des@des.no (=?iso-8859-1?q?Dag-Erling_Sm=F8rgrav?=)
To:        fandino@ng.fadesa.es
Cc:        freebsd-current@freebsd.org
Subject:   Re: FreeBSD 5.3b7and poor ata performance
Message-ID:  <xzp6552yj7d.fsf@dwp.des.no>
In-Reply-To: <41763534.2060505@ng.fadesa.es> (fandino@ng.fadesa.es's message of "Wed, 20 Oct 2004 11:51:48 %2B0200")
References:  <94275.1098221474@critter.freebsd.dk> <41763534.2060505@ng.fadesa.es>

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fandino <fandino@ng.fadesa.es> writes:
> yes, I run dd, bonnie++, bonnie and reports are very clear, there is
> a problem with performance and the ata system (I think).

There is no problem with the ATA subsystem in general.  I have no
trouble getting 40 MBps with raw sequential reads on my laptop and 50
MBps on my desktop (both running -CURRENT with INVARIANTS but no
WITNESS, and both with fairly old disks).  Unfortunately, my AMD64 box
is not online right now or I could give you the numbers for its brand-
new SATA150 drive under 5.3 BETA7.

There may be problems with your particular hardware and / or software
configuration, but you're not likely to get those solved by being so
confrontational.

As regards block sizes: there *is* a definite increase in performance
- almost a full order of magnitude - going from 512 B to 64 kB.  For
larger block sizes, you will get a smaller improvement simply from
amortizing the syscall overhead over larger transfers.  I have no idea
how Emmanuel Strobl managed to test performance with block sizes of
128 B and 256 B since the transfer size for an ATA disk needs to be a
multiple of 512 B.

DES
--=20
Dag-Erling Sm=F8rgrav - des@des.no



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