Converting from osmo_fd to osmo_io allows us to switch to the new
io_uring backend and benefit from related performance benefits.
In a benchmark running 200 concurrent bi-directional voice calls with
GSM-EFR codec, I am observing:
* the code before this patch uses 40..42% of a single core on a
Ryzen 5950X at 200 calls (=> 200 endpoints with each two connections)
* no increase in CPU utilization before/after this patch, i.e. the
osmo_io overhead for the osmo_fd backend is insignificant compared
to the direct osmo_fd mode before
* an almost exactly 50% reduction of CPU utilization when running the
same osmo-mgw build with LIBOSMO_IO_BACKEND=IO_URING - top shows
19..21% for the same workload instead of 40..42% with the OSMO_FD
default backend.
* An increase of about 4 Megabytes in both RSS and VIRT size when
enabling the OSMO_IO backend. This is likely the memory-mapped rings.
No memory leakage is observed when using either of the backends.
Change-Id: I8471960d5d8088a70cf105f2f40dfa5d5458169a
Harald Welte
352b967d1b