Reduce taskqueue congestion caused by ZFS ZIO pipeline activity
ZFS has concept of parent-child ZIOs to guide I/O requests through different stack layers. It is typical to have at least 3 ZIO per I/O. In many cases such submissions and completions are handled asynchronously via taskqueue(9) mechanism, that makes the last to be called multiple times per each I/O, that creates heavy lock congestion burning much CPU time and increasing latency at high IOPS no matter how many other measures are taken.
#1 Updated by Alexander Motin about 2 years ago
- Status changed from Unscreened to Ready for Testing
ZoL patch merged through FreeBSD head to freenas/11-stable branch: https://github.com/freenas/os/commit/c99ff0d882d586f6952e9dde17a0cf571e7f2f07
Testing may just include basic ZFS operation under load and in different scenarios. Performance testing we can leave to upstream and nap@.