diff options
| author | Kent Overstreet <kent.overstreet@linux.dev> | 2022-10-21 15:19:08 -0400 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2022-10-21 15:42:08 -0400 |
| commit | a3e79c34a8c58ddba425dc80d163b6f90dc2ca84 (patch) | |
| tree | acee238592c606d2d93ec69a4c27297dcb1e5c92 | |
| parent | 76cd6c6e69bfda8504c1584dab572896e2b2bcf2 (diff) | |
bcachefs: Cacheline align & prefetch journal reservations
Writing to the new journal entries is currently a major cacheline miss
in the transaction commit path - this helps. Additionally, this patch
cacheline aligns journal reservations, so that when multiple threads are
doing transaction commits they won't conflict.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
| -rw-r--r-- | fs/bcachefs/journal.h | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/bcachefs/journal.h b/fs/bcachefs/journal.h index d3caa7ea7ce9..ca8b5bd148a1 100644 --- a/fs/bcachefs/journal.h +++ b/fs/bcachefs/journal.h @@ -304,15 +304,26 @@ static inline int journal_res_get_fast(struct journal *j, { union journal_res_state old, new; u64 v = atomic64_read(&j->reservations.counter); + unsigned u64s, offset; do { old.v = new.v = v; /* + * Round up the end of the journal reservation to the next + * cacheline boundary: + */ + u64s = res->u64s; + offset = sizeof(struct jset) / sizeof(u64) + + new.cur_entry_offset + u64s; + u64s += ((offset - 1) & ((SMP_CACHE_BYTES / sizeof(u64)) - 1)) + 1; + + + /* * Check if there is still room in the current journal * entry: */ - if (new.cur_entry_offset + res->u64s > j->cur_entry_u64s) + if (new.cur_entry_offset + u64s > j->cur_entry_u64s) return 0; EBUG_ON(!journal_state_count(new, new.idx)); @@ -320,7 +331,7 @@ static inline int journal_res_get_fast(struct journal *j, if ((flags & JOURNAL_WATERMARK_MASK) < j->watermark) return 0; - new.cur_entry_offset += res->u64s; + new.cur_entry_offset += u64s; journal_state_inc(&new); /* @@ -337,8 +348,15 @@ static inline int journal_res_get_fast(struct journal *j, res->ref = true; res->idx = old.idx; + res->u64s = u64s; res->offset = old.cur_entry_offset; res->seq = le64_to_cpu(j->buf[old.idx].data->seq); + + offset = res->offset; + while (offset < res->offset + res->u64s) { + prefetchw(vstruct_idx(j->buf[res->idx].data, offset)); + offset += SMP_CACHE_BYTES / sizeof(u64); + } return 1; } |