ZAP: Massively switch to _by_dnode() interfaces

Before this change ZAP called dnode_hold() for almost every block
access, that was clearly visible in profiler under heavy load, such
as BRT.  This patch makes it always hold the dnode reference between
zap_lockdir() and zap_unlockdir().  It allows to avoid most of dnode
operations between those.  It also adds several new _by_dnode() APIs
to ZAP and uses them in BRT code.  Also adds dmu_prefetch_by_dnode()
variant and uses it in the ZAP code.

After this there remains only one call to dmu_buf_dnode_enter(),
which seems to be unneeded.  So remove the call and the functions.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #15951
This commit is contained in:
Alexander Motin
2024-03-25 17:58:50 -04:00
committed by GitHub
parent bf8f72359d
commit 80cc516295
9 changed files with 202 additions and 172 deletions
+2 -2
View File
@@ -752,8 +752,6 @@ void dmu_buf_sub_user_size(dmu_buf_t *db, uint64_t nsub);
void *dmu_buf_get_user(dmu_buf_t *db);
objset_t *dmu_buf_get_objset(dmu_buf_t *db);
dnode_t *dmu_buf_dnode_enter(dmu_buf_t *db);
void dmu_buf_dnode_exit(dmu_buf_t *db);
/* Block until any in-progress dmu buf user evictions complete. */
void dmu_buf_user_evict_wait(void);
@@ -902,6 +900,8 @@ extern uint_t zfs_max_recordsize;
*/
void dmu_prefetch(objset_t *os, uint64_t object, int64_t level, uint64_t offset,
uint64_t len, enum zio_priority pri);
void dmu_prefetch_by_dnode(dnode_t *dn, int64_t level, uint64_t offset,
uint64_t len, enum zio_priority pri);
void dmu_prefetch_dnode(objset_t *os, uint64_t object, enum zio_priority pri);
typedef struct dmu_object_info {