K 10 svn:author V 3 mav K 8 svn:date V 27 2018-01-22T00:19:50.338850Z K 7 svn:log V 872 MFC r322245: MFV r322242: 8373 TXG_WAIT in ZIL commit path illumos/illumos-gate@d28671a3b094af696bea87f52272d4c4d89321c7 https://github.com/illumos/illumos-gate/commit/d28671a3b094af696bea87f52272d4c4d89321c7 https://www.illumos.org/issues/8373 The code that writes ZIL blocks uses dmu_tx_assign(TXG_WAIT) to assign a transaction to a transaction group. That seems to be logically incorrect as writing of the ZIL block does not introduce any new dirty data. Also, when there is a lot of dirty data, the call can introduce significant delays into the ZIL commit path, thus affecting all synchronous writes. Additionally, ARC throttling may affect the ZIL writing. Reviewed by: Matthew Ahrens Reviewed by: Prakash Surya Approved by: Dan McDonald Author: Andriy Gapon END