# Re: \[PATCH v3\] samples/bpf: Add xdp\_stat sample program

- From: Andrii Nakryiko \<hidden\>
- Date: 2020-01-30 18:52:16 
- List: netdev
- Page: https://ratatoskr.run/netdev/2020/01/7726915
- Thread: https://ratatoskr.run/bpf/2019/12/7724661/t.md

```text
On Tue, Jan 28, 2020 at 7:55 PM Eric Sage [ref] wrote:
>
> At Facebook we use tail calls to jump between our firewall filters and
> our L4LB. This is a program I wrote to estimate per program performance
> by swapping out the entries in the program array with interceptors that
> take measurements and then jump to the original entries.
>
> I found the sample programs to be invaluable in understanding how to use
> the libbpf API (as well as the test env from the xdp-tutorial repo for
> testing), and want to return the favor. I am currently working on
> my next iteration that uses fentry/fexit to be less invasive,
> but I thought it was an interesting PoC of what you can do with program
> arrays.
>
> Signed-off-by: Eric Sage <redacted>
> ---

Looks good, thanks!

Acked-by: Andrii Nakryiko <redacted>

> Changes in v3:
> - Fixed typos in xdp_stat_kern.c
> - Switch to using key_size, value_size for prog arrays.
>

Just for the future: you should keep entire changelog, starting from
v1->v2 changes. Also, netdev patches usually preserve them as part of
commit message (for individual patch) or cover letter (for patch set).
But in this case I think changes are not substantial enough to record
them permanently, so it's fine.


[...]
```