# Re: Documenting MS\_LAZYTIME - List: linux-api - 4 messages, 3 authors - Page: https://ratatoskr.run/linux-api/2015/02/92877/t ## Re: Documenting MS\_LAZYTIME - From: Michael Kerrisk (man-pages) \ - Date: 2015-02-26 08:49:39 - Message: https://ratatoskr.run/linux-api/2015/02/92877.md ```text Ted, On 02/21/2015 03:56 AM, Theodore Ts'o wrote: > On Fri, Feb 20, 2015 at 09:49:34AM -0600, Eric Sandeen wrote: >> >>> This mount option significantly reduces writes to the >>> inode table for workloads that perform frequent random >>> writes to preallocated files. >> >> This seems like an overly specific description of a single workload out >> of many which may benefit, but what do others think? "inode table" is also >> fairly extN-specific. > > How about somethign like "This mount significantly reduces writes > needed to update the inode's timestamps, especially mtime and actime. What is "actime" in the preceding line? Should it be "ctime"? > Examples of workloads where this could be a large win include frequent > random writes to preallocated files, as well as cases where the > MS_STRICTATIME mount option is enabled."? I think some version of the following text could also usefully go into the page, but... > (The advantage of MS_STRICTATIME | MS_LAZYTIME is that stat system > calls will return the correctly updated atime, but those atime updates > won't get flushed to disk unless the inode needs to be updated for > file system / data consistency reasons, or when the inode is pushed > out of memory, or when the file system is unmounted.) I find the wording of there a little confusing. Is the following a correct rewrite: 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.) ? 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-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html ``` ## Re: Documenting MS\_LAZYTIME - From: Theodore Ts'o \ - Date: 2015-02-26 13:31:19 - Message: https://ratatoskr.run/linux-api/2015/02/92881.md ```text On Thu, Feb 26, 2015 at 09:49:39AM +0100, Michael Kerrisk (man-pages) wrote: > > How about somethign like "This mount significantly reduces writes > > needed to update the inode's timestamps, especially mtime and actime. > > What is "actime" in the preceding line? Should it be "ctime"? Sorry, no, it should be "atime". > I find the wording of there a little confusing. Is the following > a correct rewrite: > > 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.) Yes, that's correct. The only other thing I might add is that in the case of a crash, the atime (or mtime) fields on disk might be out of date by at most 24 hours. - Ted ``` ## Re: Documenting MS\_LAZYTIME - From: Michael Kerrisk (man-pages) \ - Date: 2015-02-26 13:36:33 - Message: https://ratatoskr.run/linux-api/2015/02/92882.md ```text On 02/26/2015 02:31 PM, Theodore Ts'o wrote: > On Thu, Feb 26, 2015 at 09:49:39AM +0100, Michael Kerrisk (man-pages) wrote: >>> How about somethign like "This mount significantly reduces writes >>> needed to update the inode's timestamps, especially mtime and actime. >> >> What is "actime" in the preceding line? Should it be "ctime"? > > Sorry, no, it should be "atime". Thanks. >> I find the wording of there a little confusing. Is the following >> a correct rewrite: >> >> 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.) > > Yes, that's correct. The only other thing I might add is that in the > case of a crash, the atime (or mtime) fields on disk might be out of > date by at most 24 hours. So in other words, add a sentence to that last para: 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. Right? Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs ``` ## Re: Documenting MS\_LAZYTIME - From: Theodore Ts'o \ - Date: 2015-02-27 00:04:15 - Message: https://ratatoskr.run/linux-api/2015/02/92904.md ```text 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? - Ted ```