On 20 February 2015 at 13:32, Andreas Dilger <adilger@xxxxxxxxx> wrote:
> On Feb 20, 2015, at 1:50 AM, Michael Kerrisk <mtk.manpages@xxxxxxxxx> wrote:
>>
>> Hello Ted,
>>
>> Based on your commit message 0ae45f63d4e, I I wrote the documentation
>> below for MS_LAZYTIME, to go into the mount(2) man page. Could you
>> please check it over and let me know if it's accurate. In particular,
>> I added pieces marked with "*" below that were not part of the commit
>> message and I'd like confirmation that they're accurate.
>>
>> Thanks,
>>
>> Michael
>>
>> [[
>> MS_LAZYTIME (since Linux 3.20)
>> Only update filetimes (atime, mtime, ctime) on the in-
>> memory version of the file inode. The on-disk timeâ
>> stamps are updated only when:
>>
>> (a) the inode needs to be updated for some change unreâ
>> 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 i-node was
>> * written to disk.
>>
>> This mount option significantly reduces writes to the
>> inode table for workloads that perform frequent random
>> writes to preallocated files.
>>
>> * As at Linux 3.20, this option is supported only on ext4.
>
> I _think_ that the lazytime mount option is generic for all filesystems.
> I believe ext4 has an extra optimization for it, but that's it.
Ah yes, looking at the code again, that makes sense. I think you're
right, and I've struck that last sentence. Thanks, Andreas.
Cheers,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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