K 10 svn:author V 3 avg K 8 svn:date V 27 2017-08-08T11:24:13.843681Z K 7 svn:log V 1000 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. We probably need a new mechanism similar to dmu_tx_create_assigned to assign ZIL transactions. (Ab)using TXG_WAITED does not seem to be sufficient. Reviewed by: Matthew Ahrens Reviewed by: Prakash Surya Approved by: Dan McDonald Author: Andriy Gapon END