From 5a28a9737ade6a9c1014d8e7f286431fad9f382e Mon Sep 17 00:00:00 2001 From: Matthew Ahrens Date: Wed, 4 Nov 2015 21:37:33 +0100 Subject: [PATCH] Illumos 6288 - dmu_buf_will_dirty could be faster 6288 dmu_buf_will_dirty could be faster Reviewed by: George Wilson Reviewed by: Paul Dagnelie Reviewed by: Justin Gibbs Reviewed by: Richard Elling Approved by: Robert Mustacchi References: https://www.illumos.org/issues/6288 https://github.com/illumos/illumos-gate/commit/0f2e7d0 Porting notes: - [module/zfs/dbuf.c] - Fix 'warning: ISO C90 forbids mixed declarations and code' by moving 'dbuf_dirty_record_t *dr' to start of code block. Ported-by: kernelOfTruth kerneloftruth@gmail.com Signed-off-by: Brian Behlendorf --- module/zfs/dbuf.c | 62 +++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 52 insertions(+), 10 deletions(-) diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c index d53d8607a..e65f573e2 100644 --- a/module/zfs/dbuf.c +++ b/module/zfs/dbuf.c @@ -1182,6 +1182,32 @@ dbuf_release_bp(dmu_buf_impl_t *db) (void) arc_release(db->db_buf, db); } +/* + * We already have a dirty record for this TXG, and we are being + * dirtied again. + */ +static void +dbuf_redirty(dbuf_dirty_record_t *dr) +{ + dmu_buf_impl_t *db = dr->dr_dbuf; + + ASSERT(MUTEX_HELD(&db->db_mtx)); + + if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) { + /* + * If this buffer has already been written out, + * we now need to reset its state. + */ + dbuf_unoverride(dr); + if (db->db.db_object != DMU_META_DNODE_OBJECT && + db->db_state != DB_NOFILL) { + /* Already released on initial dirty, so just thaw. */ + ASSERT(arc_released(db->db_buf)); + arc_buf_thaw(db->db_buf); + } + } +} + dbuf_dirty_record_t * dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) { @@ -1254,16 +1280,7 @@ dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) if (dr && dr->dr_txg == tx->tx_txg) { DB_DNODE_EXIT(db); - if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) { - /* - * If this buffer has already been written out, - * we now need to reset its state. - */ - dbuf_unoverride(dr); - if (db->db.db_object != DMU_META_DNODE_OBJECT && - db->db_state != DB_NOFILL) - arc_buf_thaw(db->db_buf); - } + dbuf_redirty(dr); mutex_exit(&db->db_mtx); return (dr); } @@ -1564,10 +1581,35 @@ dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx) { dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH; + dbuf_dirty_record_t *dr; ASSERT(tx->tx_txg != 0); ASSERT(!refcount_is_zero(&db->db_holds)); + /* + * Quick check for dirtyness. For already dirty blocks, this + * reduces runtime of this function by >90%, and overall performance + * by 50% for some workloads (e.g. file deletion with indirect blocks + * cached). + */ + mutex_enter(&db->db_mtx); + + for (dr = db->db_last_dirty; + dr != NULL && dr->dr_txg >= tx->tx_txg; dr = dr->dr_next) { + /* + * It's possible that it is already dirty but not cached, + * because there are some calls to dbuf_dirty() that don't + * go through dmu_buf_will_dirty(). + */ + if (dr->dr_txg == tx->tx_txg && db->db_state == DB_CACHED) { + /* This dbuf is already dirty and cached. */ + dbuf_redirty(dr); + mutex_exit(&db->db_mtx); + return; + } + } + mutex_exit(&db->db_mtx); + DB_DNODE_ENTER(db); if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock)) rf |= DB_RF_HAVESTRUCT;