Date: Wed, 26 Nov 2014 13:06:33 -0500
From: Marcus Reid <marcus@blazingdot.com>
To: freebsd-current@freebsd.org, freebsd-fs@freebsd.org
Subject: Delayed atime updates ("lazytime")
Message-ID: <20141126180633.GA69028@blazingdot.com>
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Hi, Looks like Linux is about to grow another solution to handling atime updates differently: http://lwn.net/SubscriberLink/621046/e59938475fd3e874/ In short, it will only write out atime changes periodically (daily), or if there is another reason to write out the inode, or if the inode is about to be pushed out of cache. This seems like a pretty good compromise. Currently, the ZFS configuration that results from using bsdinstall disables atime on all but /var/mail, which is the only example of disabling atime by default that I'm aware of outside of Gentoo Linux. I can't seem to find any information that talks about the rationale behind that, though a couple things come to mind: - some additional IO generated (but that's always been the case) - additional wear on SSD devices (enough to compel the change?) - zfs snapshot growth (but the snapshot stops growing after one full set of inode updates) - wake up otherwise idle spinning media on a laptop (the actual reason that was cited as motivation for the change) Something like lazytime would address most of those concerns, and people who are even more OCD than that could disable atime completely on their machine. Marcus
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