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author | Kent Overstreet <kent.overstreet@linux.dev> | 2024-04-05 23:27:27 -0400 |
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committer | Kent Overstreet <kent.overstreet@linux.dev> | 2024-04-06 13:50:26 -0400 |
commit | 6088234ce83acec4aaf56ecc0e9525bac18b4295 (patch) | |
tree | b72e80255b37eaba6b7574b56f5391277b5635cd /fs/bcachefs/btree_update_interior.c | |
parent | 05801b6526156aefe55c0440fab877109c9a89c5 (diff) | |
download | linux-stable-6088234ce83acec4aaf56ecc0e9525bac18b4295.tar.gz linux-stable-6088234ce83acec4aaf56ecc0e9525bac18b4295.tar.bz2 linux-stable-6088234ce83acec4aaf56ecc0e9525bac18b4295.zip |
bcachefs: JOURNAL_SPACE_LOW
"bcachefs; Fix deadlock in bch2_btree_update_start()" was a significant
performance regression (nearly 50%) on multithreaded random writes with
fio.
The reason is that the journal watermark checks multiple things,
including the state of the btree write buffer, and on multithreaded
update heavy workloads we're bottleneked on write buffer flushing - we
don't want kicknig off btree updates to depend on the state of the write
buffer.
This isn't strictly correct; the interior btree update path does do
write buffer updates, but it's a tiny fraction of total accounting
updates and we're more concerned with space in the journal itself.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs/btree_update_interior.c')
-rw-r--r-- | fs/bcachefs/btree_update_interior.c | 18 |
1 files changed, 7 insertions, 11 deletions
diff --git a/fs/bcachefs/btree_update_interior.c b/fs/bcachefs/btree_update_interior.c index 24fbd5be70a2..a4a63e363047 100644 --- a/fs/bcachefs/btree_update_interior.c +++ b/fs/bcachefs/btree_update_interior.c @@ -1125,18 +1125,14 @@ bch2_btree_update_start(struct btree_trans *trans, struct btree_path *path, flags &= ~BCH_WATERMARK_MASK; flags |= watermark; - if (watermark < c->journal.watermark) { - struct journal_res res = { 0 }; - unsigned journal_flags = watermark|JOURNAL_RES_GET_CHECK; + if (watermark < BCH_WATERMARK_reclaim && + test_bit(JOURNAL_SPACE_LOW, &c->journal.flags)) { + if (flags & BCH_TRANS_COMMIT_journal_reclaim) + return ERR_PTR(-BCH_ERR_journal_reclaim_would_deadlock); - if ((flags & BCH_TRANS_COMMIT_journal_reclaim) && - watermark < BCH_WATERMARK_reclaim) - journal_flags |= JOURNAL_RES_GET_NONBLOCK; - - ret = drop_locks_do(trans, - bch2_journal_res_get(&c->journal, &res, 1, journal_flags)); - if (bch2_err_matches(ret, BCH_ERR_operation_blocked)) - ret = -BCH_ERR_journal_reclaim_would_deadlock; + bch2_trans_unlock(trans); + wait_event(c->journal.wait, !test_bit(JOURNAL_SPACE_LOW, &c->journal.flags)); + ret = bch2_trans_relock(trans); if (ret) return ERR_PTR(ret); } |