[LU-14712] make TRIM state persistent across reboots

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0, Lustre 2.17.0
• 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

Comments

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/59312/
Subject: LU-14712 ldiskfs: keep EXT4_BG_TRIMMED flag in memory
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: ebb7c944a0115852fdcb0b32b078aed28292b054

[Gerrit Updater]

"Li Dongyang <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/tools/e2fsprogs/+/59313
Subject: LU-14712 e2fsprogs: rename EXT2_FLAGS_TRACK_TRIM to EXT2_FLAGS_NO_TRIM_TRACKING
Project: tools/e2fsprogs
Branch: master-lustre
Current Patch Set: 1
Commit: 462883fe18f63de9dc196fc83d451c3d1f2ff290

[Gerrit Updater]

"Li Dongyang <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/59312
Subject: LU-14712 ldiskfs: rename EXT2_FLAGS_TRACK_TRIM to EXT2_FLAGS_NO_TRIM_TRACKING
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: d8993774eeae80ffa3b31e7c8ab00654dadfdf9c

[Dongyang Li]

Yes indeed we should use EXT2_BG_TRIMMED, the commit message and the debian/changelog wording should be fixed in the next release.

[Andreas Dilger]

Sorry, you are right. I was on the wrong branch and "git grep BG_TRIM" did not return anything. I see it now.

I also noticed it is also a bit confusing that debian/changelog reports "e2fsprogs: support EXT2_FLAG_BG_TRIMMED and EXT2_FLAGS_TRACK_TRIM" instead of EXT2_BG_TRIMMED that the flag is actually named.

I wanted to check whether doing the "full device discard" during mke2fs would mark all of the groups with EXT2_BG_TRIMMED. It looks like this is the case:

                retval_discard = io_channel_discard(fs->io, start, count);
                if (!retval_discard) {
                        ext2fs_bg_flags_set(fs, group, EXT2_BG_TRIMMED);
                        ext2fs_group_desc_csum_set(fs, group);
                        fs->super->s_flags |= EXT2_FLAGS_TRACK_TRIM;

[Andreas Dilger]

dongyang I just noticed that we do not have the patches to support the EXT4_BG_TRIMMED flag in the Lustre e2fsprogs release. Could you please include those patches in the next release.

[Peter Jones]

Merged for 2.16

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/55567/
Subject: LU-14712 ldiskfs: add bg_trimmed_threshold interface
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 7ac01793a3d451700fee3be6b655c4494ee158aa

[Peter Jones]

Seems to be another patch tracked under this ticket

[Gerrit Updater]

"Li Dongyang <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/55567
Subject: LU-14712 ldiskfs: add bg_trimmed_threshold interface
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 7222197b34c4f2b9dc87805bc3806279041c8fe5