[LU-17309] set timestamp on llog objects at creation time

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.17.0
• Affects Version/s: Lustre 2.15.0
• Labels: easy
• Severity: 3
• Assignee: Keguang Xu
• Reporter: Andreas Dilger

Description

For debugging purposes, it would be useful to store the ctime for an llog object when it is created. Otherwise, the objects currently do not set any timestamp on the log even though it was recently created (e.g. the 39xx logs, the low-numbered 2015 objects were created with an older Lustre version):

     9851      4 -rw-r--r--   1  root     root            8 Nov  7  2013 /mnt/tmp/O/1/LAST_ID
     1850     20 -rw-r--r--   1  root     root        19584 May  6  2015 /mnt/tmp/O/1/d4/164
    98363     12 -rw-r--r--   1  root     root         8448 Dec 31  1969 /mnt/tmp/O/1/d4/3972
     1665     20 -rw-r--r--   1  root     root        17792 May  6  2015 /mnt/tmp/O/1/d0/160
     1849     12 -rw-r--r--   1  root     root         8256 Apr 23  2015 /mnt/tmp/O/1/d30/158
     1861     20 -rw-r--r--   1  root     root        17472 May  6  2015 /mnt/tmp/O/1/d6/166
    98365     12 -rw-r--r--   1  root     root         8448 Dec 31  1969 /mnt/tmp/O/1/d6/3974
  2130157     12 -rw-r--r--   1  root     root         8384 Dec 31  1969 /mnt/tmp/O/1/d8/3976

The same with logs in CONFIGS:

# debugfs -c -R "ls -l CONFIGS" /dev/loop0
debugfs 1.46.6-wc1 (10-Jan-2023)
     13   40755 (2)      0      0    4096  5-Mar-2024 12:58 .
      2   40755 (2)      0      0    4096  5-Mar-2024 12:58 ..
     14  100644 (1)      0      0   12288  5-Mar-2024 12:58 mountdata
     82  100644 (1)      0      0    8192 31-Dec-1969 17:00 nodemap
     85  100644 (1)      0      0   11008 31-Dec-1969 17:00 params
     86  100644 (1)      0      0   69600 31-Dec-1969 17:00 testfs-client
     87  100644 (1)      0      0   75560 31-Dec-1969 17:00 testfs-MDT0000
    154  100644 (1)      0      0   75024 31-Dec-1969 17:00 testfs-MDT0001
    156  100644 (1)      0      0   74488 31-Dec-1969 17:00 testfs-MDT0002
    158  100644 (1)      0      0   73952 31-Dec-1969 17:00 testfs-MDT0003
    160  100644 (1)      0      0   17992 31-Dec-1969 17:00 testfs-OST0000
    161  100644 (1)      0      0   17680 31-Dec-1969 17:00 testfs-OST0001
    169  100644 (1)      0      0   17144 31-Dec-1969 17:00 testfs-OST0002
    170  100644 (1)      0      0   16608 31-Dec-1969 17:00 testfs-OST0003

Similarly, it would also be useful to update the mtime when a catalog is modified, since this doesn't happen very often and otherwise they show the timestamp when the file was created (maybe not even that for newer versions of Lustre):

    4 -rw-r--r--.  1 root        160 May  6  2015 CATALOGS
  180 -rw-r--r--.  1 root     176576 Nov  7  2013 changelog_catalog
   12 -rw-r--r--.  1 root       8384 Nov  7  2013 changelog_users

There is no overhead to update the mtime when new records are added to an llog file, since the new inode size/blocks needs to be written anyway.

Comments

[Alex Zhuravlev]

squalfof please check https://review.whamcloud.com/c/fs/lustre-release/+/57510
I benchmarked with ldiskfs, you can use sanity/60a as a reference.

[Keguang Xu]

Will look after it.

• Any scripts/commands to reproduce this issue?
• And environment? Ldiskfs or ZFS?

Thanks.

[Alex Zhuravlev]

updating attributes every time we add a record has a significant performance penalty:
with timestamp:

[   12.236741] Lustre: took 76627 waiting, 2394 us / rec in 1 threads
[   13.341116] Lustre: took 60811 waiting, 1900 us / rec in 4 threads

without timestamp:

[   12.218171] Lustre: took 68078 waiting, 2127 us / rec in 1 threads
[   13.323605] Lustre: took 53228 waiting, 1663 us / rec in 4 threads

[Peter Jones]

Merged for 2.17

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/56691/
Subject: LU-17309 llog: set timestamp on llog objects at creation time
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: e33d196b937957f257590d823088e0cda388a11e

[Gerrit Updater]

"kg.xu <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/56691
Subject: LU-17309 llog: set timestamp on llog objects at creation time
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 718583bccdf7f4c675f7cffc592c1b846bec2647