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
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opensolaris	MFV r315290, r315291: 7303 dynamic metaslab selection	2017-03-24 09:37:00 +00:00