netdev - Re: [PATCH bpf-next v5 0/6] xdp: Add devmap

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Message-ID: <CAADnVQJpYeQ68V5BE2r3BhbraBh7G8dSd8zknFUJxtW4GwNkuA@mail.gmail.com>
Date:   Fri, 26 Jul 2019 19:26:16 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Toke Høiland-Jørgensen <toke@...hat.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Network Development <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Björn Töpel <bjorn.topel@...il.com>,
        Yonghong Song <yhs@...com>
Subject: Re: [PATCH bpf-next v5 0/6] xdp: Add devmap_hash map type

On Fri, Jul 26, 2019 at 9:06 AM Toke Høiland-Jørgensen <toke@...hat.com> wrote:
>
> This series adds a new map type, devmap_hash, that works like the existing
> devmap type, but using a hash-based indexing scheme. This is useful for the use
> case where a devmap is indexed by ifindex (for instance for use with the routing
> table lookup helper). For this use case, the regular devmap needs to be sized
> after the maximum ifindex number, not the number of devices in it. A hash-based
> indexing scheme makes it possible to size the map after the number of devices it
> should contain instead.
>
> This was previously part of my patch series that also turned the regular
> bpf_redirect() helper into a map-based one; for this series I just pulled out
> the patches that introduced the new map type.
>
> Changelog:
>
> v5:
>
> - Dynamically set the number of hash buckets by rounding up max_entries to the
>   nearest power of two (mirroring the regular hashmap), as suggested by Jesper.

fyi I'm waiting for Jesper to review this new version.