Date: Thu, 24 May 2001 23:19:44 -0700 From: Doug Barton <DougB@DougBarton.net> To: Ed Hudson <elh_fbsd@spnet.com> Cc: hackers@FreeBSD.ORG Subject: Re: general speed differences between 4.1.1-RELEASE and 4.3-RELEASE Message-ID: <3B0DF980.EDA844F7@DougBarton.net> References: <200105250025.f4P0Pu905553@m44.spnet.com>
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Ed Hudson wrote:
>
> fyi, here's another hw.ata.wc=1 vs hw.ata.wc=0 comparison:
>
> 4.3-RELEASE install, ASUS A7V, 800mhz, hw.ata.wc=0, express install +all,
> 60gig wd-600b udma100 drive, partitioned as:
>
> / 8192m
> swap 1024m
> /xtra 48023m
>
> installed from 52x cdrom.
> install time: 27minutes, 38 seconds (1658 seconds).
>
> a modified 4.3-RELEASE install iso (modified by replacing /floppies/boot.flp
> loader.rc/support.4th and adding a loader.conf, setting hw.ata.wc=1) file,
> written to cd.
>
> same partition, same install (express + all)
>
> install time: 8minutes, 59 seconds ( 539 seconds)
>
> 4.3-with-wc=1 / 4.3-with-wc=0 : 3.07x
>
> in both installation cases both filesystems were newfs'd, but the
> speed difference is evident everywhere during the install.
>
> i would urge the FreeBSD lords to consider mr. silbersack's proposal
> of either remaking hw.ata.wc=1 the default,
The current mood (which I agree with) is to make softupdates the default
after installation. The problem with the combo of write caching and
softupdates is that if the power actually goes off the meta-data writes
that softupdates postpones and are further postponed by the write cache
will never happen, therefore leaving the file system in a potentially
unrecoverable state.
> or at least, consider making this the default for the base install.
This would work for situations where it's being installed to a clean disk,
but might be trouble when installing over an existing installation. The
problem (as I understand it) is that the write cache option can only be
enabled at boot time. If I'm wrong about this, it'd be a good thing to
enable if we're sure we're newfs'ing the partitions we're installing to.
Doug
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