SYSCTL_COUNTER_U64_ARRAY() macro.
- Add proper asserts to the SYSCTL_COUNTER_U64_ARRAY() macro that checks
the size of the first element of the array.
- Add an example to the counter(9) manual page how to use the
SYSCTL_COUNTER_U64_ARRAY() macro.
- Add some missing symbolic links for counter(9) while at it.
Fix logic error in the description of counter_u64_alloc: the command
may fail only if M_NOWAIT is specified, not M_WAITOK.
Reviewed by: glebius
MFC after: 2 weeks
Sponsored by: Spectra Logic Corporation
Introduce counter(9) API, that implements fast and raceless counters,
provided (but not limited to) for gathering of statistical data.
See http://lists.freebsd.org/pipermail/freebsd-arch/2013-April/014204.html
for more details.
In collaboration with: kib
Reviewed by: luigi
Tested by: ae, ray
Sponsored by: Nginx, Inc.
