netdev - Re: [PATCH bpf-next v2 1/2] trace_helpers.c: Add helpers to poll multiple perf FDs for events

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Date:   Tue, 5 Jun 2018 01:42:24 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jakub Kicinski <kubakici@...pl>,
        Toke Høiland-Jørgensen 
        <toke@...e.dk>
Cc:     netdev@...r.kernel.org,
        Alexei Starovoitov <alexei.starovoitov@...il.com>
Subject: Re: [PATCH bpf-next v2 1/2] trace_helpers.c: Add helpers to poll
 multiple perf FDs for events

On 06/05/2018 12:26 AM, Jakub Kicinski wrote:
> On Mon, 04 Jun 2018 18:33:56 +0200, Toke Høiland-Jørgensen wrote:
>> This adds two new helper functions to trace_helpers that supports polling
>> multiple perf file descriptors for events. These are used to the XDP
>> perf_event_output example, which needs to work with one perf fd per CPU.
>>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@...e.dk>
> 
> Did you take a look at tools/bpf/bpftool/map_perf_ring.c ?
> 
> I think the ability to poll multiple FDs could be generally useful and
> therefore better add it to libbpf.c than
> tools/testing/selftests/bpf/trace_helpers.c?  I'm not 100% sure myself...

I think for it to land in libbpf this code needs to be more generalized
as it is right now and allowing for more flexibility like pinning RB
processing threads to CPUs, poll handling, etc.