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From: "Toke Høiland-Jørgensen" <toke@kernel.org>
To: Ujwal Kundur <ujwal.kundur@gmail.com>,
	Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net,
	kuba@kernel.org, hawk@kernel.org, john.fastabend@gmail.com,
	andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com,
	song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org,
	sdf@fomichev.me, aoluo@google.com, jolsa@kernel.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] bpf: cpumap: report Rx queue index to xdp_rxq_info
Date: Tue, 10 Jun 2025 22:24:34 +0200	[thread overview]
Message-ID: <87msafcpkt.fsf@toke.dk> (raw)
In-Reply-To: <CALkFLLJpz2MxRZ8r+mGayU_BZE=2=ukXTzXcnmyhXeHB7Q6v3g@mail.gmail.com>

Ujwal Kundur <ujwal.kundur@gmail.com> writes:

>> This looks wrong...
>> I think this will always return index 0
>
>> So passing dev->_rx to that function will always return 0; which is what
>> the field is already initialised to...
>
> I didn't realize that would always return 0, sorry I should've tried
> to understand that statement better.
>
>> I'll just add that you may want to take a look at Lorenzo's series[0].
>> Rx queue index is sorta HW hint, so it shouldn't be a problem to add the
>> corresponding field to xdp_rx_meta.
>> Then, you can expand cpumap's code to try reading that HW meta if present.
>
> Thank you! I also tried to work backwards to figure out how the
> queue_index would be used if present in xdp_rxq_info but that wasn't
> immediately apparent to me.
> I'm keen on learning/contributing to the BPF part of the network stack
> and this seemed like a good first patch to take up -- I'll understand
> this better and try again.

Sounds good! Don't be discouraged by having to try again, that's
perfectly normal :)

-Toke

      reply	other threads:[~2025-06-10 20:24 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-09 17:38 [PATCH] bpf: cpumap: report Rx queue index to xdp_rxq_info Ujwal Kundur
2025-06-10 11:29 ` Jesper Dangaard Brouer
2025-06-10 12:01 ` Toke Høiland-Jørgensen
2025-06-10 13:15 ` Alexander Lobakin
2025-06-10 14:02   ` Ujwal Kundur
2025-06-10 20:24     ` Toke Høiland-Jørgensen [this message]

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