Re: [PATCH bpf-next 0/5] introduce bpf_strncmp() helper

On Tue, Nov 30, 2021 at 6:07 AM Hou Tao [off-list ref] wrote:

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.

I think 'home made' strncmp could have been written
differently. I bet in bpf assembly it would be much closer
in performance if not the same,
but the helper is useful.
The patch set doesn't apply cleanly.
Pls respin.