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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
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drivers i40e: Use batched xsk Tx interfaces to increase performance 2020-11-17 22:07:40 +01:00
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include bpf: Add bpf_ktime_get_coarse_ns helper 2020-11-18 23:25:32 +01:00
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kernel bpf: Add bpf_ktime_get_coarse_ns helper 2020-11-18 23:25:32 +01:00
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net xsk: Introduce batched Tx descriptor interfaces 2020-11-17 22:07:40 +01:00
samples samples/bpf: Increment Tx stats at sending 2020-11-17 22:07:40 +01:00
scripts bpf: Add bpf_bprm_opts_set helper 2020-11-18 01:36:27 +01:00
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tools bpf: Add bpf_ktime_get_coarse_ns helper 2020-11-18 23:25:32 +01:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.