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From: Bruce Cran <bruce@cran.org.uk>
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Date: Sat, 5 Jun 2010 02:36:17 +0100
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Cc: Adam PAPAI <wooh@wooh.hu>, freebsd-questions@freebsd.org
Subject: Re: sysbench / fileio - Linux vs. FreeBSD
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On Saturday 05 June 2010 00:58:35 Adam PAPAI wrote:

> Why FreeBSD is supreme with 1 and 2 thread. And why is it 2 and 3 times
> slower with 4-8-16-32 threads compared to Debian? The first two tests (1
> thread and 2 thread) showed me that FreeBSD is supreme in I/O, but later
> tests showed me, that it can produce horrible I/O.
> 
> How can I tune my disk to make it faster? Is it possible? What is the
> reason of the really slow I/O with more than 4 threads? What do you
> recommend me to do? Why is it damn slow with 8K blocksize?

Some quick tests show that ufs does do rather poorly on my system too. I have 
the following filesystems setup:

/var : ufs with softupdates
/usr/obj : zfs with checksums disabled
/usr/src : zfs with compression enabled
/home   : zfs with compression disabled and checksums enabled

I ran a test with a blocksize of 8KB and 16 threads.

/var       : 25.2MB/s
/usr/obj : 64.8MB/s
/usr/src : 386.3MB/s
/home   : 60.3MB/s

-- 
Bruce Cran