diff options
| author | Brian Behlendorf <[email protected]> | 2016-12-01 16:50:11 -0700 |
|---|---|---|
| committer | GitHub <[email protected]> | 2016-12-01 16:50:11 -0700 |
| commit | b0319c1faae5a77e553ae74bf899efbc6629674d (patch) | |
| tree | 55af2150425f0d4b2afad4c30d80ef406db82f80 /module/zfs/dbuf.c | |
| parent | ba712624d6a0df121d5dfc5440ba83cf53224916 (diff) | |
OpenZFS 7143 - dbuf_read() creates unnecessary zio_root() for bonus buf
dbuf_read() creates a zio_root() to track and wait for all the
zio's that may happen as part of this call. However, if the blkptr_t
for this buffer is NULL or a hole, we will not create any more zio's,
so this zio_root() is unnecessary. This is always the case when calling
dbuf_read() on a bonus buffer, because it has no blkptr (it's part of
the containing dnode). For workloads that read a lot of bonus buffers
(e.g. file creation and removal), creating and destroying these
unnecessary zio's can decrease performance by around 3%.
The fix is to only create/destroy the zio_root() in dbuf_read() if
the blkptr is not NULL and not a hole.
Changes sponsored by Intel Corp.
Authored by: Matthew Ahrens <[email protected]>
Reviewed-by: Alex Zhuravlev <[email protected]>
Ported-by: Brian Behlendorf <[email protected]>
Issue openzfs/openzfs#137
Closes #4803
Closes #5382
Diffstat (limited to 'module/zfs/dbuf.c')
| -rw-r--r-- | module/zfs/dbuf.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c index f7857134c..cfa4fd1fc 100644 --- a/module/zfs/dbuf.c +++ b/module/zfs/dbuf.c @@ -21,7 +21,7 @@ /* * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. * Copyright 2011 Nexenta Systems, Inc. All rights reserved. - * Copyright (c) 2012, 2016 by Delphix. All rights reserved. + * Copyright (c) 2012, 2015 by Delphix. All rights reserved. * Copyright (c) 2013 by Saso Kiselkov. All rights reserved. * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved. */ @@ -1207,7 +1207,8 @@ dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags) } else if (db->db_state == DB_UNCACHED) { spa_t *spa = dn->dn_objset->os_spa; - if (zio == NULL) + if (zio == NULL && + db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL); err = dbuf_read_impl(db, zio, flags); @@ -1221,7 +1222,7 @@ dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags) rw_exit(&dn->dn_struct_rwlock); DB_DNODE_EXIT(db); - if (!err && !havepzio) + if (!err && !havepzio && zio != NULL) err = zio_wait(zio); } else { /* |