On Fri, 10 Aug 2007 15:09:11 +0200 Ralf Corsepius rc040203@freenet.de wrote:
On Fri, 2007-08-10 at 07:59 -0400, James Hubbard wrote:
On 8/9/07, Ralf Corsepius rc040203@freenet.de wrote:
IMO, disabling atime by default, just because 99% of applications, don't use it, is short-sighted. It basically ditches a fundamental feature of unix filessystems and converts there behavior to "DOS'ish".
If it's such a fundamental feature that should be kept around, why have NFS optimization documents always recommended disabling atime updates especially on servers where there is a lot of throughput?
I don't know.
Just because it's a fundamental feature doesn't mean that it has to be used. Fundamentally, my CPU can run at 2GHz all of the time that doesn't mean that it should. If 99% of the applications can do without it and probably 99% of the people can as well, why not go ahead and get disable it.
That's what people call "arrogance of the masses". Let's kill that 1%, if 99% don't care!
<sarcasm> It's the same argument why people argue against utf-8, work as root (don't need uid/gids) and don't want SELinux?
Let's remove all of this from the kernel, single seat/single user systems don't need all this at all.
</sarcasm>
Those that need atime will eventually figure out how to turn it on. The potential for a better user experience as well possible power savings seems to outweigh the fundamental feature argument.
A friend of mine experimented with atime/noatime yesterday:
These were his results:
Test case: A heavy weight compiler-job
Default /etc/fstab real 5m18.226s user 4m44.557s sys 1m17.193s User+Sys: 365.750
Rebooted -- all filesystems noatime,nodiratime real 5m4.256s user 4m36.841s sys 1m8.364s User+Sys: 346.750
new / old = .9465
[Fedora-7, i386 on an AMD Athlon(tm) 64 X2 Dual Core Processor 3800+]
Way off from the figures the proponents of notime are reporting.
Well... a heavy compile job isn't going to reflect that much because you're writing to the disk anyway.
Perhaps try doing a 'find / -exec cat {} > /dev/null ;' with and without atime.
josh