netdev - Re: [PATCH v3 net-next] bpf/verifier: track liveness for pruning

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Message-ID: <599371EA.20605@iogearbox.net>
Date:   Wed, 16 Aug 2017 00:12:58 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Edward Cree <ecree@...arflare.com>, davem@...emloft.net,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Alexei Starovoitov <ast@...com>
CC:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        iovisor-dev <iovisor-dev@...ts.iovisor.org>
Subject: Re: [PATCH v3 net-next] bpf/verifier: track liveness for pruning

On 08/15/2017 09:34 PM, Edward Cree wrote:
> State of a register doesn't matter if it wasn't read in reaching an exit;
>   a write screens off all reads downstream of it from all explored_states
>   upstream of it.
> This allows us to prune many more branches; here are some processed insn
>   counts for some Cilium programs:
> Program                  before  after
> bpf_lb_opt_-DLB_L3.o       6515   3361
> bpf_lb_opt_-DLB_L4.o       8976   5176
> bpf_lb_opt_-DUNKNOWN.o     2960   1137
> bpf_lxc_opt_-DDROP_ALL.o  95412  48537
> bpf_lxc_opt_-DUNKNOWN.o  141706  78718
> bpf_netdev.o              24251  17995
> bpf_overlay.o             10999   9385
>
> The runtime is also improved; here are 'time' results in ms:
> Program                  before  after
> bpf_lb_opt_-DLB_L3.o         24      6
> bpf_lb_opt_-DLB_L4.o         26     11
> bpf_lb_opt_-DUNKNOWN.o       11      2
> bpf_lxc_opt_-DDROP_ALL.o   1288    139
> bpf_lxc_opt_-DUNKNOWN.o    1768    234
> bpf_netdev.o                 62     31
> bpf_overlay.o                15     13
>
> Signed-off-by: Edward Cree <ecree@...arflare.com>

Acked-by: Daniel Borkmann <daniel@...earbox.net>