From owner-freebsd-scsi  Sat Oct  3 18:37:58 1998
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Date: Sun, 4 Oct 1998 11:37:22 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199810040137.LAA14507@godzilla.zeta.org.au>
To: bde@zeta.org.au, tlambert@primenet.com
Subject: Re: filesystem safety and SCSI disk write caching
Cc: Don.Lewis@tsc.tdk.com, freebsd-fs@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG,
        gibbs@plutotech.com
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>> I think it can be interpreted as showing that the performance hit is
>> very large.  `make world' is mostly cpu-bound, and most of it's i/o's
>> are reads (60% here).  I guess it spends less than 5 minutes of its time
>> writing (27000 block output operations here).  An increase of 5 minutes
>> is very large.
>
>This is without "noatime".

Actually, 27000 is with "noatime" on all file systems, and with "async"
on all file systems that were written to by my `make world' (/tmp, /var/tmp,
MAKEOBJDIRPREFIX = /c/obj and DESTDIR = /c/root).

>Every inode read, is written, and every
>directory inode is written multiple times, and all object files and
>executables, as well as some generated sources, are written.

Yes, the default configuration may be much slower than mine.

Bruce

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