Date: Wed, 6 Oct 1999 18:15:42 -0500
From: "Matthew D. Fuller" <fullermd@futuresouth.com>
To: Peter Jeremy <peter.jeremy@alcatel.com.au>
Cc: freebsd-current@FreeBSD.ORG
Subject: {a}sync updates (was Re: make install trick)
Message-ID: <19991006181542.S20768@futuresouth.com>
In-Reply-To: <99Oct7.085536est.40332@border.alcanet.com.au>
References: <99Oct6.103524est.40351@border.alcanet.com.au> <Pine.BSF.4.05.9910051831180.6368-100000@fw.wintelcom.net> <99Oct6.145359est.40347@border.alcanet.com.au> <19991006154419.O20768@futuresouth.com> <99Oct7.085536est.40332@border.alcanet.com.au>
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Thank you, this is *EXACTLY* what I was looking for :)
On Thu, Oct 07, 1999 at 08:59:00AM +1000, a little birdie told me
that Peter Jeremy remarked
>
> As far as I can tell, the net effect is that inode access time updates
> will remain async writes into the filesystem.
>
> An easy way to tell would be to use NOATIME and see if you're still
> getting async writes. (Or any writes at all).
This does appear to be it.
Testing such things as (cat /kernel >> /dev/null && sync && sync)
preceded and followed by a 'mount' call in another window does show the
'async' counter incrementing, and when I remount it noatime it no longer
does.
Is this good, bad, ugly, or just inconsistent? On the one hand, you can
argue that 'sync should be sync should be sync, I don't bloody care, just
don't do anything async at all', since that's what it's supposed to do:
mount(8):
sync All I/O to the file system should be done synchronously.
On the gripping hand, you can say, 'this is an ATIME update, there's no
way its presence or lack thereof can do anything bad to the filesystem,
so let it be async since it takes extra work to make it sync'.
Does anyone have any feeling either way on this? I, unfortunately, seem
to have strong feelings BOTH ways... sync atime updates will slow it
down, but on the flip side, if you're mounting sync in the first place
you don't care much for speed anyway.
Thoughts?
--
Matthew Fuller (MF4839) | fullermd@over-yonder.net
Unix Systems Administrator | fullermd@futuresouth.com
Specializing in FreeBSD | http://www.over-yonder.net/
FutureSouth Communications | ISPHelp ISP Consulting
"The only reason I'm burning my candle at both ends, is because I
haven't figured out how to light the middle yet"
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