Austin S. Hemmelgarn posted on Mon, 14 Dec 2015 15:27:11 -0500 as excerpted:
> FWIW, both Duncan and I have our own copy of the sources patched to > default to noatime, and I know a number of embedded Linux developers who > do likewise, and I've even heard talk in the past of some distributions > possibly using such patches themselves (although it always ends up not > happening, because of Mutt). And FWIW, while I was reasonably conservative with my original patch and simply defaulted to noatime, turning it off if any of the atime-enabling options were found, I'm beginning to think I might as well simply hard- code noatime, removing the conditions. This is due to initr* behavior that ends up not disabling atime for early, mostly virtual/memory-based filesystems like procfs, sysfs, devfs, tmp-on-tmpfs, etc, but could extend to initial initr* mount of the root filesystem as well, if I decide to make it rw on the kernel commandline or some such. Of course atime on a memory-based-fs isn't normally a huge problem since its all memory-based anyway, and it would enable stuff like atime based tmpwatch since I do a tmpfs based tmp, so I've not worried about it much. But at the same time, I'm now assuming noatime on my systems, and anything that breaks that assumption could trigger hard to trace down bugs, and hardcoding the noatime assumption would bring a consistency that I don't have ATM. If/when I change my patch in that regard, I may look into adding other conditional options, perhaps defaulting to autodefrag if it's btrfs, for instance, if my limited sysadmin-not-developer-level patching/coding skills allow it. I'd have to see... But I'd certainly start with making autodefrag a default, not hard-coded, if I did patch in autodefrag, because while I don't have large VM images and the like, where autodefrag can be a performance bottleneck, to worry about now, I'd like to keep that option available for me in the future, and would thus make autodefrag the default, not hard-coded. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
