zfsonlinux/zfs — pull request #1513 by dweeezil (2013-06-11 20:50:39+00:00)
Title: Illumos #3552, #3564

3552 condensing one space map burns 3 seconds of CPU in spa_sync() thread
3564 spa_sync() spends 5-10% of its time in metaslab_sync() (when not condensing)
Reviewed by: Adam Leventhal
Reviewed by: Dan Kimmel
Reviewed by: Matthew Ahrens
Approved by: Richard Lowe

References:
illumos/illumos-gate@16a4a8074274d2d7cc408589cf6359f4a378c861
https://www.illumos.org/issues/3552
https://www.illumos.org/issues/3564

ZoL porting notes:

This commit is based on dweeezil/zfs@f2ee66346b44a755faa4d4e8d43d9aed940d4541 in order
to get the Illumos #3006 changes.

Ported-by: Tim Chase