Re: BPF memstore and bpf_validate_ext()

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

Alexander Nasonov <alnsn%yandex.ru@localhost> wrote:
> > > 
> > > If this is the case, you don't need BPF_COP at all.
> > 
> > For this particular case - yes, correct.
> > 
> > > Except of course you may run out or memwords one day and you want
> > > to have BPF_COP as a fallback.
> > 
> > I still need BPF_COP for other tasks (e.g. NPF_COP_TABLE).  Running out
> > of words is unlikely, but COP can certainly be used to handle that too.
> 
> I wonder why do you need two different features when one is a
> superset of the other if you could use BPF_COP?

The fact that you can abuse one feature to achieve the result of another
does not mean that it is a good solution.  Using the external memory store
and initialising/passing some values is just simple and straightforward,
besides being faster.

> <...> If the only reason
> is performance, external memory is not a win-win proposition.

You mean because using EREG penalises the access of the memstore?  I doubt
it is a big deal, but can we just benchmark and see?

-- 
Mindaugas