[LU-19158] export fstrim statistics from ext4/ldiskfs

• Type: Improvement
• Resolution: Fixed
• Priority: Medium
• Fix Version/s: Lustre 2.17.0
• Affects Version/s: Lustre 2.14.0, Lustre 2.16.1
• Labels: easy medium
• Severity: 3
• Assignee: Dongyang Li
• Reporter: Andreas Dilger

Description

For tracking the size and frequency of fstrim operations in an ldiskfs filesystem, it would be useful to export statistics in /sys/fs/ldiskfs/BDEV/ and/or /proc/fs/ldiskfs/BDEV/ that report the count and size of TRIM operations sent to the underlying storage.

This is useful both for the existing manual fstrim calls, as well as ongoing -o discard and future -o fstrim functionality being added in LU-17980.

I'm thinking something like:

• /sys/fs/ldiskfs/BDEV/lifetime_fstrim_kbytes - integer like .../lifetime_write_kbytes
• /sys/fs/ldiskfs/BDEV/lifetime_fstrim_ops - integer of the number of trim operations (can work out average size together with .../lifetime_fstrim_kbytes
• /proc/fs/ldiskfs/BDEV/fstrim_stats - YAML histogram of trim operations by size, something like:

  count: 987
  sizes: { 4KB:   123, 64KB: 345, 256KB: 2, 512KB: 103, 1024KB: 32, 4096KB: 4, 131072kB: 378 }
  

Issue Links

• is related to: LU-17980 improve ldiskfs "-o discard" performance