[netbsdusers]

Solaris achieved some kind of integration between the ARC and the VM subsystem as part of the VM2 project. I don't know any more details than that.

[ryao]

I assume that the VM2 project achieved something similar to the ABD changes that were done in OpenZFS. ABD replaced the use of SLAB buffers for ARC with lists of pages. The issue with SLAB buffers is that absurd amounts of work could be done to free memory, and a single long lived SLAB object would prevent any of it from mattering. Long lived slab objects caused excessive reclaim, slowed down the process of freeing enough memory to satisfy system needs and in some cases, prevented enough memory from being freed to satisfy system needs entirely. Switching to linked lists of pages fixed that since the memory being freed from ARC upon request would immediately become free rather than be deferred to when all of the objects in the SLAB had been freed.