netdev - Re: [PATCH 1/3] bpf: allow zero-initializing hash map seed

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Message-ID: <20181005210732.ft77r5qqcoqpiwu7@ast-mbp.dhcp.thefacebook.com>
Date:   Fri, 5 Oct 2018 14:07:34 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Jann Horn <jannh@...gle.com>
Cc:     lmb@...udflare.com, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Network Development <netdev@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>
Subject: Re: [PATCH 1/3] bpf: allow zero-initializing hash map seed

On Fri, Oct 05, 2018 at 04:27:58PM +0200, Jann Horn wrote:
> 
> Can you please describe exactly why something that is not a kernel
> unit test needs deterministic BPF hash map behavior?

my use case for deterministic hashing is performance analysis.
Both while developing and tuning bpf program and while optimizing
kernel side implementation.
Local dos is a valid concern, so requiring root for this flag makes sense.