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Date: Sun, 14 Apr 2002 21:40:58 +0200
From: Pavel Machek <pavel@suse.cz>
To: Jamie Lokier <lk@tantalophile.demon.co.uk>
Cc: linux-kernel@vger.kernel.org
Subject: Re: faster boots?
Message-ID: <20020414194058.GA4269@atrey.karlin.mff.cuni.cz>
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Hi!

> > >     while :; do cat /proc/stat; sleep 1; done
> > > 
> > > Then I see a few writes have occurred at nearly every iteration.  I
> > > think that is due to the atime updates, because using "noatime" there
> > > are no writes at most iterations.
> > 
> > Well, that's no problem. noflushd stops kflushd, so it should work
> > even with atime. [It works for me with atimes!]
> > 
> > > But more interesting: I only see those few-per-second atime writes while
> > > noflushd is running.  If I kill noflushd then they go away.
> > 
> > ?
> 
> Another curious thing: even if the regular writes were caused by atime
> updates, there is no reason for them to be flushed every second, is
> there?
> 
> Yet the hard disk light flashes about once per second when (a) running
> the above shell line and (b) running noflushd, and (c) _not_ using
> "noatime" (just "nodiratime").  (Remove any of those and it stops).  And
> /proc/stat shows writes happening.
> 
> This is on ext3.  I wonder if journalling is causing a problem.  Pavel,
> are you running ext3?

No, plain old ext2. Yep, ext3 could have some strange interactions
with noflushd.
								Pavel
-- 
Casualities in World Trade Center: ~3k dead inside the building,
cryptography in U.S.A. and free speech in Czech Republic.
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