Dmitrii Banshchikov d055126180 bpf: Add bpf_ktime_get_coarse_ns helper
The helper uses CLOCK_MONOTONIC_COARSE source of time that is less
accurate but more performant.

We have a BPF CGROUP_SKB firewall that supports event logging through
bpf_perf_event_output(). Each event has a timestamp and currently we use
bpf_ktime_get_ns() for it. Use of bpf_ktime_get_coarse_ns() saves ~15-20
ns in time required for event logging.

bpf_ktime_get_ns():
EgressLogByRemoteEndpoint                              113.82ns    8.79M

bpf_ktime_get_coarse_ns():
EgressLogByRemoteEndpoint                               95.40ns   10.48M

Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201117184549.257280-1-me@ubique.spb.ru
2020-11-18 23:25:32 +01:00
..
2020-09-11 09:33:54 -07:00
2020-11-01 11:08:17 -08:00
2020-11-10 18:31:17 +01:00
\n
2020-08-06 19:29:51 -07:00
2020-08-26 09:10:39 -04:00
2020-08-04 14:20:26 -07:00
2020-06-03 13:06:42 -07:00
2020-10-22 13:13:57 -07:00
2020-10-16 11:11:22 -07:00
2020-10-18 09:27:10 -07:00
2020-07-01 12:09:13 +03:00
2020-07-27 14:31:12 -04:00
2019-12-18 18:07:31 +01:00
2020-06-04 19:06:24 -07:00
2020-07-07 11:58:59 -05:00
2020-05-09 13:57:12 +02:00