MFV r315290, r315291: 7303 dynamic metaslab selection

illumos/illumos-gate@8363e80ae72609660f6090766ca8c2c18aa53f0c
https://github.com/illumos/illumos-gate/commit/8363e80ae72609660f6090766ca8c2c18

https://www.illumos.org/issues/7303

  This change introduces a new weighting algorithm to improve metaslab selection.
  The new weighting algorithm relies on the SPACEMAP_HISTOGRAM feature. As a result,
  the metaslab weight now encodes the type of weighting algorithm used
  (size-based vs segment-based).

  This also introduce a new allocation tracing facility and two new dcmds to help
  debug allocation problems. Each zio now contains a zio_alloc_list_t structure
  that is populated as the zio goes through the allocations stage. Here's an
  example of how to use the tracing facility:

> c5ec000::print zio_t io_alloc_list | ::walk list | ::metaslab_trace
  MSID    DVA    ASIZE      WEIGHT             RESULT               VDEV
     -      0      400           0    NOT_ALLOCATABLE           ztest.0a
     -      0      400           0    NOT_ALLOCATABLE           ztest.0a
     -      0      400           0             ENOSPC           ztest.0a
     -      0      200           0    NOT_ALLOCATABLE           ztest.0a
     -      0      200           0    NOT_ALLOCATABLE           ztest.0a
     -      0      200           0             ENOSPC           ztest.0a
     1      0      400      1 x 8M            17b1a00           ztest.0a

> 1ff2400::print zio_t io_alloc_list | ::walk list | ::metaslab_trace
  MSID    DVA    ASIZE      WEIGHT             RESULT               VDEV
     -      0      200           0    NOT_ALLOCATABLE           mirror-2
     -      0      200           0    NOT_ALLOCATABLE           mirror-0
     1      0      200      1 x 4M            112ae00           mirror-1
     -      1      200           0    NOT_ALLOCATABLE           mirror-2
     -      1      200           0    NOT_ALLOCATABLE           mirror-0
     1      1      200      1 x 4M            112b000           mirror-1
     -      2      200           0    NOT_ALLOCATABLE           mirror-2

  If the metaslab is using segment-based weighting then the WEIGHT column will
  display the number of segments available in the bucket where the allocation
  attempt was made.

Author: George Wilson <george.wilson@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: Chris Siden <christopher.siden@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Don Brady <don.brady@intel.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

1 files changed, 10 insertions, 3 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/metaslab.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/metaslab.h
index 592aea5869cb..84c17c1c14da 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/metaslab.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/metaslab.h
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2016 by Delphix. All rights reserved.
  */
 
 #ifndef _SYS_METASLAB_H
@@ -36,10 +36,12 @@
 extern "C" {
 #endif
 
+
 typedef struct metaslab_ops {
-	uint64_t (*msop_alloc)(metaslab_t *msp, uint64_t size);
+	uint64_t (*msop_alloc)(metaslab_t *, uint64_t);
 } metaslab_ops_t;
 
+
 extern metaslab_ops_t *zfs_metaslab_ops;
 
 int metaslab_init(metaslab_group_t *, uint64_t, uint64_t, uint64_t,
@@ -63,11 +65,16 @@ uint64_t metaslab_block_maxsize(metaslab_t *);
 #define	METASLAB_DONT_THROTTLE		0x10
 
 int metaslab_alloc(spa_t *, metaslab_class_t *, uint64_t,
-    blkptr_t *, int, uint64_t, blkptr_t *, int, zio_t *);
+    blkptr_t *, int, uint64_t, blkptr_t *, int, zio_alloc_list_t *, zio_t *);
 void metaslab_free(spa_t *, const blkptr_t *, uint64_t, boolean_t);
 int metaslab_claim(spa_t *, const blkptr_t *, uint64_t);
 void metaslab_check_free(spa_t *, const blkptr_t *);
 
+void metaslab_alloc_trace_init(void);
+void metaslab_alloc_trace_fini(void);
+void metaslab_trace_init(zio_alloc_list_t *);
+void metaslab_trace_fini(zio_alloc_list_t *);
+
 metaslab_class_t *metaslab_class_create(spa_t *, metaslab_ops_t *);
 void metaslab_class_destroy(metaslab_class_t *);
 int metaslab_class_validate(metaslab_class_t *);