Re: FreeBSD 5.3b7and poor ata performance

From: Dag-Erling Smørgrav <des_at_des.no>
Date: Fri, 22 Oct 2004 15:29:42 +0200
fandino <fandino_at_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
-- 
Dag-Erling Smørgrav - des_at_des.no
Received on Fri Oct 22 2004 - 11:29:51 UTC

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