- reorder structures fields (XX_refs) a bit to group fields modified
same time together. According to my tests it gives up to 10%
SMP performance benefit on real workload due to reduced inter-CPU
cache trashing.
- change q_flags from long to int as long is not really needed there and
it's usage with atomics is argued by some people.
- move NGF_WORKQ flag into the separate field q_flags2 as it protected by
queue mutex instead of node writer protection used by the rest of flags.
- move nd_work queue entry to ng_queue structure to which it is more
related and make it STAILQ instead of TAILQ as now it is a classic FIFO.
- remove q_node pointer from ng_queue structure as it is not really needed.
- reimplement item queue using STAILQ instead of own equal implementation.
As soon as BT subsystem has own item queues using ng_item.el_next update
it also.
- change depth field in ng_item from uintptr_t to u_int. It was made
uintptr_t to keep ABI compatibility.
Reviewed by: julian, emax
Tested with: Netperf cluster
9852972bb5