Hello Omar, On 02/27/2015 09:08 AM, Omar Sandoval wrote: > On Fri, Feb 27, 2015 at 09:01:10AM +0100, Michael Kerrisk (man-pages) wrote: >> On 02/27/2015 01:04 AM, Theodore Ts'o wrote: >>> On Thu, Feb 26, 2015 at 02:36:33PM +0100, Michael Kerrisk (man-pages) wrote: >>>> >>>> The disadvantage of MS_STRICTATIME | MS_LAZYTIME is that >>>> in the case of a system crash, the atime and mtime fields >>>> on disk might be out of date by at most 24 hours. >>> >>> I'd change to "The disadvantage of MS_LAZYTIME is that..." and >>> perhaps move that so it's clear it applies to any use of MS_LAZYTIME >>> has this as a downside. >>> >>> Does that make sense? >> >> Thanks, Ted. Got it. So, now we have: >> >> MS_LAZYTIME (since Linux 3.20) >> Reduce on-disk updates of inode timestamps (atime, >> mtime, ctime) by maintaining these changes only in mem‐ >> ory. The on-disk timestamps are updated only when: >> >> (a) the inode needs to be updated for some change unre‐ >> lated to file timestamps; >> >> (b) the application employs fsync(2), syncfs(2), or >> sync(2); >> >> (c) an undeleted inode is evicted from memory; or >> >> (d) more than 24 hours have passed since the inode was >> written to disk. >> >> This mount significantly reduces writes needed to update > "This mount option"? Thanks, fixed. >> the inode's timestamps, especially mtime and atime. >> However, in the event of a system crash, the atime and >> mtime fields on disk might be out of date by up to 24 >> hours. >> >> Examples of workloads where this option could be of sig‐ >> nificant benefit include frequent random writes to pre‐ >> allocated files, as well as cases where the MS_STRICTA‐ >> TIME mount option is also enabled. (The advantage of >> (MS_STRICTATIME | MS_LAZYTIME) is that stat(2) will >> return the correctly updated atime, but the atime >> updates will be flushed to disk only when (1) the inode >> needs to be updated for filesystem / data consistency >> reasons or (2) the inode is pushed out of memory, or (3) >> the filesystem is unmounted.) > Is it necessary to repeat the reasons for flushing, which are stated > above? Good point. I replaced this piece with just a few words referring to the list above. Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
