Rob Norris db2db50e37 spa: make read/write queues configurable ... We are finding that as customers get larger and faster machines (hundreds of cores, large NVMe-backed pools) they keep hitting relatively low performance ceilings. Our profiling work almost always finds that they're running into bottlenecks on the SPA IO taskqs. Unfortunately there's often little we can advise at that point, because there's very few ways to change behaviour without patching. This commit adds two load-time parameters `zio_taskq_read` and `zio_taskq_write` that can configure the READ and WRITE IO taskqs directly. This achieves two goals: it gives operators (and those that support them) a way to tune things without requiring a custom build of OpenZFS, which is often not possible, and it lets us easily try different config variations in a variety of environments to inform the development of better defaults for these kind of systems. Because tuning the IO taskqs really requires a fairly deep understanding of how IO in ZFS works, and generally isn't needed without a pretty serious workload and an ability to identify bottlenecks, only minimal documentation is provided. Its expected that anyone using this is going to have the source code there as well. Signed-off-by: Rob Norris <rob.norris@klarasystems.com> Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc.		2023-12-22 13:25:07 -08:00
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spl.4	Add a delay to tearing down threads.	2023-06-26 13:57:12 -07:00
zfs.4	spa: make read/write queues configurable	2023-12-22 13:25:07 -08:00