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Illumos 6288 - dmu_buf_will_dirty could be faster

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6288 dmu_buf_will_dirty could be faster
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Justin Gibbs <gibbs@scsiguy.com>
Reviewed by: Richard Elling <Richard.Elling@RichardElling.com>
Approved by: Robert Mustacchi <rm@joyent.com>

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 <behlendorf1@llnl.gov>
This commit is contained in:
Matthew Ahrens 2015-11-04 21:37:33 +01:00 committed by Brian Behlendorf
parent 2e8efe1bef
commit 5a28a9737a
1 changed files with 52 additions and 10 deletions
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62
module/zfs/dbuf.c
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@ -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;