From: Hou Tao <houtao1@huawei.com>
To: Alexei Starovoitov <ast@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>, Yonghong Song <yhs@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, <netdev@vger.kernel.org>,
<bpf@vger.kernel.org>, <houtao1@huawei.com>
Subject: [PATCH bpf-next 0/5] introduce bpf_strncmp() helper
Date: Tue, 30 Nov 2021 22:22:10 +0800 [thread overview]
Message-ID: <20211130142215.1237217-1-houtao1@huawei.com> (raw)
Hi,
The motivation for introducing bpf_strncmp() helper comes from
two aspects:
(1) clang doesn't always replace strncmp() automatically
In tracing program, sometimes we need to using a home-made
strncmp() to check whether or not the file name is expected.
(2) the performance of home-made strncmp is not so good
As shown in the benchmark in patch #4, the performance of
bpf_strncmp() helper is 18% or 33% better than home-made strncmp()
under x86-64 or arm64 when the compared string length is 64. When
the string length grows to 4095, the performance win will be
179% or 600% under x86-64 or arm64.
The prototype of bpf_strncmp() has changed from
bpf_strncmp(const char *s1, const char *s2, u32 s2_sz)
to
bpf_strncmp(const char *s1, u32 s1_sz, const char *s2)
The main reason is readability and there is nearly no performance
difference between these two APIs (refer to the data attached below
[1]).
Any comments are welcome.
Regards,
Tao
Change Log:
v1:
* change API to bpf_strncmp(const char *s1, u32 s1_sz, const char *s2)
* add benchmark refactor and benchmark between bpf_strncmp() and strncmp()
RFC: https://lore.kernel.org/bpf/20211106132822.1396621-1-houtao1@huawei.com/
[1] Performance difference between two APIs under x86-64:
helper_rfc-X: use bpf_strncmp in RFC to compare X-sized string
helper-Y: use bpf_strncmp in v1 to compare Y-sized string
helper_rfc-1 3.482 ± 0.002M/s (drops 0.000 ± 0.000M/s)
helper-1 3.485 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper_rfc-8 3.428 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper-8 3.434 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper_rfc-32 3.253 ± 0.002M/s (drops 0.000 ± 0.000M/s)
helper-32 3.234 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper_rfc-64 3.039 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-64 3.042 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper_rfc-128 2.640 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-128 2.633 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper_rfc-512 1.576 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-512 1.574 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper_rfc-2048 0.602 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-2048 0.602 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper_rfc-4095 0.328 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-4095 0.328 ± 0.000M/s (drops 0.000 ± 0.000M/s)
Hou Tao (5):
bpf: add bpf_strncmp helper
selftests/bpf: fix checkpatch error on empty function parameter
selftests/bpf: factor out common helpers for benchmarks
selftests/bpf: add benchmark for bpf_strncmp() helper
selftests/bpf: add test cases for bpf_strncmp()
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 11 ++
kernel/bpf/helpers.c | 16 ++
tools/include/uapi/linux/bpf.h | 11 ++
tools/testing/selftests/bpf/Makefile | 4 +-
tools/testing/selftests/bpf/bench.c | 21 ++-
tools/testing/selftests/bpf/bench.h | 34 +++-
.../bpf/benchs/bench_bloom_filter_map.c | 44 ++---
.../selftests/bpf/benchs/bench_count.c | 16 +-
.../selftests/bpf/benchs/bench_rename.c | 43 ++---
.../selftests/bpf/benchs/bench_ringbufs.c | 21 +--
.../selftests/bpf/benchs/bench_strncmp.c | 150 ++++++++++++++++
.../selftests/bpf/benchs/bench_trigger.c | 79 ++++----
.../selftests/bpf/benchs/run_bench_strncmp.sh | 12 ++
.../selftests/bpf/prog_tests/test_strncmp.c | 170 ++++++++++++++++++
.../selftests/bpf/progs/strncmp_bench.c | 50 ++++++
.../selftests/bpf/progs/strncmp_test.c | 59 ++++++
17 files changed, 604 insertions(+), 138 deletions(-)
create mode 100644 tools/testing/selftests/bpf/benchs/bench_strncmp.c
create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh
create mode 100644 tools/testing/selftests/bpf/prog_tests/test_strncmp.c
create mode 100644 tools/testing/selftests/bpf/progs/strncmp_bench.c
create mode 100644 tools/testing/selftests/bpf/progs/strncmp_test.c
--
2.29.2
next reply other threads:[~2021-11-30 14:07 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 14:22 Hou Tao [this message]
2021-11-30 14:22 ` [PATCH bpf-next 1/5] bpf: add bpf_strncmp helper Hou Tao
2021-11-30 14:22 ` [PATCH bpf-next 2/5] selftests/bpf: fix checkpatch error on empty function parameter Hou Tao
2021-11-30 14:22 ` [PATCH bpf-next 3/5] selftests/bpf: factor out common helpers for benchmarks Hou Tao
2021-12-07 2:55 ` Andrii Nakryiko
2021-12-08 13:41 ` Hou Tao
2021-11-30 14:22 ` [PATCH bpf-next 4/5] selftests/bpf: add benchmark for bpf_strncmp() helper Hou Tao
2021-12-07 3:01 ` Andrii Nakryiko
2021-12-08 13:47 ` Hou Tao
2021-12-08 20:08 ` Andrii Nakryiko
2021-11-30 14:22 ` [PATCH bpf-next 5/5] selftests/bpf: add test cases for bpf_strncmp() Hou Tao
2021-12-07 3:09 ` Andrii Nakryiko
2021-12-08 13:50 ` Hou Tao
2021-12-03 2:09 ` [PATCH bpf-next 0/5] introduce bpf_strncmp() helper Alexei Starovoitov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211130142215.1237217-1-houtao1@huawei.com \
--to=houtao1@huawei.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kafai@fb.com \
--cc=netdev@vger.kernel.org \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.