Wow, this is interesting, didn't know it. I'll probably try noatime instead:) Sincerely, Nazar Mokrynskyi github.com/nazar-pc Skype: nazar-pc Diaspora: nazarpc@xxxxxxxxxxxxxxxxxxxxxxx Tox: A9D95C9AA5F7A3ED75D83D0292E22ACE84BA40E912185939414475AF28FD2B2A5C8EF5261249 On 23.02.16 18:29, Alexander Fougner wrote:
2016-02-23 18:18 GMT+01:00 Nazar Mokrynskyi <nazar@xxxxxxxxxxxxxx>:But why? I have relatime option, it should not cause changes unless file contents is actually changed if I understand this option correctly.*or* if it is older than 1 day. From the manpages: relatime Update inode access times relative to modify or change time. Access time is only updated if the previous access time was earlier than the current modify or change time. (Similar to noatime, but it doesn't break mutt or other applications that need to know if a file has been read since the last time it was modified.) Since Linux 2.6.30, the kernel defaults to the behavior provided by this option (unless noatime was specified), and the strictatime option is required to obtain traditionalsemantics. In addition, since Linux 2.6.30, the file's lastaccess time is always updated if it is more than 1 day old. <<<<< Also, if you only use relatime, then you don't need to specify it, it's the default since 2.6.30 as mentioned above.Sincerely, Nazar Mokrynskyi github.com/nazar-pc Skype: nazar-pc Diaspora: nazarpc@xxxxxxxxxxxxxxxxxxxxxxx Tox: A9D95C9AA5F7A3ED75D83D0292E22ACE84BA40E912185939414475AF28FD2B2A5C8EF5261249 On 23.02.16 18:05, Alexander Fougner wrote:2016-02-23 17:55 GMT+01:00 Nazar Mokrynskyi <nazar@xxxxxxxxxxxxxx>:What is wrong with noatime,relatime? I'm using them for a long time as good compromise in terms of performance.The one option ends up canceling the other, as they're both atime related options that say do different things. I'd have to actually setup a test or do some research to be sure which one overrides the other (but someone here probably can say without further research), tho I'd /guess/ the latter one overrides the earlier one, which would effectively make them both pretty much useless, since relatime is the normal kernel default and thus doesn't need to be specified. Noatime is strongly recommended for btrfs, however, particularly with snapshots, as otherwise, the changes between snapshots can consist mostly of generally useless atime changes. (FWIW, after over a decade of using noatime here (I first used it on the then new reiserfs, after finding a recommendation for it on that), I got tired of specifying the option on nearly all my fstab entries, and now days carry a local kernel patch that changes the default to noatime, allowing me to drop specifying it everywhere. I don't claim to be a coder, let alone a kernel level coder, but as a gentooer used to building from source for over a decade, I've found that I can often find the code behind some behavior I'd like to tweak, and given good enough comments, I can often create trivial patches to accomplish that tweak, even if it's not exactly the code a real C coder would choose to use, which is exactly what I've done here. So now, unless some other atime option is specified, my filesystems are all mounted noatime. =:^)Well, then I'll leave relatime on root fs and noatime on partition with snapshots, thanks.If you snapshot the root filesystem then the atime changes will still be there, and you'll be having a lot of unnecessary changes between each snapshot.-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
Attachment:
smime.p7s
Description: Кріптографічний підпис S/MIME
