Re: Documenting MS_LAZYTIME

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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  time‐
>>              stamps 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 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/
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux