[LU-14712] make TRIM state persistent across reboots

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0
• Labels: NVME ldiskfs performance
• Assignee: Dongyang Li
• Reporter: Andreas Dilger

Description

The current "-o discard" mount option for ldiskfs enables on-the-fly TRIM of underlying flash devices (or thinly-provisioned LUNs). However, the current implementation hurts performance because it is done synchronously in the context of the JBD2 commit thread as a commit callback, which blocks later transaction commits.

There are patches by Shilong that make the TRIM state for a block group persistent, so that running TRIM with mke2fs does not also lead to fstrim resubmitting TRIM requests for all of the groups again immediately after mount/remount.

Most recent e2fsprogs patches at:
https://patchwork.ozlabs.org/project/linux-ext4/patch/[e-mail]/
https://patchwork.ozlabs.org/project/linux-ext4/patch/[e-mail]/

ext4 kernel patch:
https://patchwork.ozlabs.org/project/linux-ext4/patch/[e-mail]/
https://patchwork.ozlabs.org/project/linux-ext4/patch/[e-mail]/

I think the combination of these two patches would improve ongoing ldiskfs performance on flash devices significantly.

Issue Links

• is cloned by: LU-17980 improve ldiskfs "-o discard" performance
• is related to: LU-16750 optimize ldiskfs internal metadata allocation for hybrid storage LUNs