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Alexander Motin 3aef5b286a MFV r315290, r315291: 7303 dynamic metaslab selection 
illumos/illumos-gate@8363e80ae7
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>
2017-03-24 09:37:00 +00:00
..
boot/zfs loader: update symlink support in zfs reader 2017-02-22 22:00:50 +00:00
compat/opensolaris MFV r315290, r315291: 7303 dynamic metaslab selection 2017-03-24 09:37:00 +00:00
contrib/opensolaris MFV r315290, r315291: 7303 dynamic metaslab selection 2017-03-24 09:37:00 +00:00
dev Fix a backwards comparison in the code to dump a DTrace debug buffer. 2017-03-13 18:43:00 +00:00