linux-ext4 - Re: [PATCH] Update atime from future.

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Date:	Tue, 11 Jan 2011 14:33:14 +0100
From:	Pavel Machek <pavel@....cz>
To:	Steven Whitehouse <swhiteho@...hat.com>
Cc:	yangsheng <sickamd@...il.com>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, adilger.kernel@...ger.ca,
	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] Update atime from future.

	return 1;
> > +	/*
> > +	 * Is the previous atime value old than a day? If yes,
> >  	 * update atime:
> >  	 */
> >  	if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
> 
> I don't think this is a good plan for cluster filesystems, since if the
> times on the nodes are not exactly synchronised (we do highly recommend
> people run ntp or similar) then this might lead to excessive atime
> updating. The current behaviour is to ignore atimes which are in the
> future for exactly this reason,

Well, would these "update storms" really be a problem?

AFAICT they should be fairly non-frequent, and worst thing that can
happen is that you'll do as many updates as different time settings,
settling for the lowest value...?
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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