linux-kernel - Re: [RFC PATCH bpf-next v2 0/6] bpf: add BPF_MAP

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Message-ID: <20190627221434.tz2fscw2cjvrqiop@ast-mbp.dhcp.thefacebook.com>
Date:   Thu, 27 Jun 2019 15:14:36 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Brian Vazquez <brianvv@...gle.com>
Cc:     Brian Vazquez <brianvv.kernel@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S . Miller" <davem@...emloft.net>,
        Stanislav Fomichev <sdf@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Petar Penkov <ppenkov@...gle.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [RFC PATCH bpf-next v2 0/6]  bpf: add BPF_MAP_DUMP command to

On Thu, Jun 27, 2019 at 01:24:11PM -0700, Brian Vazquez wrote:
> This introduces a new command to retrieve a variable number of entries
> from a bpf map.
> 
> This new command can be executed from the existing BPF syscall as
> follows:
> 
> err =  bpf(BPF_MAP_DUMP, union bpf_attr *attr, u32 size)
> using attr->dump.map_fd, attr->dump.prev_key, attr->dump.buf,
> attr->dump.buf_len
> returns zero or negative error, and populates buf and buf_len on
> succees
> 
> This implementation is wrapping the existing bpf methods:
> map_get_next_key and map_lookup_elem
> the results show that even with a 1-elem_size buffer, it runs ~40 faster
> than the current implementation, improvements of ~85% are reported when
> the buffer size is increased, although, after the buffer size is around
> 5% of the total number of entries there's no huge difference in
> increasing
> it.

was it with kpti and retpoline mitigations?