Re: [PATCH net-next 8/8] netfilter: flowtable: add hardware offload tracepoints

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Sat, Mar 12, 2022 at 10:05:55PM +0200, Vlad Buslov wrote:
> 
> On Mon 07 Mar 2022 at 23:49, Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > On Tue, Feb 22, 2022 at 05:10:03PM +0200, Vlad Buslov wrote:
> >> Add tracepoints to trace creation and start of execution of flowtable
> >> hardware offload 'add', 'del' and 'stats' tasks. Move struct
> >> flow_offload_work from source into header file to allow access to structure
> >> fields from tracepoint code.
> >
> > This patch, I would prefer to keep it back and explore exposing trace
> > infrastructure for the flowtable through netlink.
> >
> 
> What approach do you have in mind with netlink? I used tracepoints here
> because they are:
> 
> - Incur no performance penalty when disabled.
> 
> - Handy to attach BPF programs to.
> 
> According to my experience with optimizing TC control path parsing
> Netlink is CPU-intensive. I am also not aware of mechanisms to leverage
> it to attach BPF.

Sure, no question tracing and introspection is useful.

But could you use the generic workqueue trace points instead?

This is adding tracing infrastructure for a very specific purpose, to
inspect the workqueue behaviour for the flowtable.

And I am not sure how you use this yet other than observing that the
workqueue is coping with the workload?