Build problems fixed:
- void* pointer arithmetic which is a GNU extension (works as byte*)
- "variable size object may not be initialized" which is OK under GCC
- nullptr_t related error in json11 (it lacks 'operator <' in clang)
Warnings fixed:
- empty nested struct initializer { 0 } replaced by {}
- removed several unused lambda captures
Prelimilary results:
- CPU usage drops significantly. For example, in T1Q8 128K write test against
stub_uring_osd with 10G network and Athlon X4 860k CPU it drops from 100% to 30%
- Latency becomes slightly worse. In T1Q1 4K write test in the same environment
latency increases from 56 to 63 us.
- Small write throughput also becomes slightly worse. In T1Q128 4K write test
against stub iops decreases from 138k to ~110k (unstable, fluctuates 100k..120k).
Note that this is without io_uring, of course.