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([2601:282:803:7700:2529:5ed3:9969:3b0e]) by smtp.googlemail.com with ESMTPSA id o6sm3260849ilm.74.2020.02.02.13.51.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 02 Feb 2020 13:51:06 -0800 (PST) Subject: Re: [PATCH bpf-next 03/12] net: Add IFLA_XDP_EGRESS for XDP programs in the egress path To: Jakub Kicinski Cc: =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= , netdev@vger.kernel.org, prashantbhole.linux@gmail.com, jasowang@redhat.com, davem@davemloft.net, jbrouer@redhat.com, mst@redhat.com, toshiaki.makita1@gmail.com, daniel@iogearbox.net, john.fastabend@gmail.com, ast@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, andriin@fb.com References: <20200123014210.38412-1-dsahern@kernel.org> <20200123014210.38412-4-dsahern@kernel.org> <87tv4m9zio.fsf@toke.dk> <335b624a-655a-c0c6-ca27-102e6dac790b@gmail.com> <20200124072128.4fcb4bd1@cakuba> <87o8usg92d.fsf@toke.dk> <1d84d8be-6812-d63a-97ca-ebc68cc266b9@gmail.com> <20200126141141.0b773aba@cakuba> <33f233a9-88b4-a75a-d1e5-fbbda21f9546@gmail.com> <20200127061623.1cf42cd0@cakuba> <252acf50-91ff-fdc5-3ce1-491a02de07c6@gmail.com> <20200128055752.617aebc7@cakuba> <20200202113152.321b665f@cakuba.hsd1.ca.comcast.net> From: David Ahern Message-ID: <89fb234d-b6fe-cc96-52f5-7ed310ee9dff@gmail.com> Date: Sun, 2 Feb 2020 14:51:04 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <20200202113152.321b665f@cakuba.hsd1.ca.comcast.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2/2/20 12:31 PM, Jakub Kicinski wrote: > > I think our perspectives will be difficult to reconcile. > > My reading is that you look at this from slow software device > perspective. Of which there are few (and already loaded with hacks). > And you want the control plane to be simple rather than performance. > > I look at this from HW driver perspective of which there are many. > Saying that it's fine to load TX paths of all drivers with extra > code, and that it's fine to effectively disable SG in the entire > system just doesn't compute. > > Is that a fair summary of the arguments? > I do not believe so. My argument is about allowing XDP and full stack to work synergistically: Fast path for known unicast traffic, and slow path for BUM traffic without duplicating config such as ACLs and forcing a specific design (such as forcing all programs in the XDP Rx path which does not work for all traffic patterns). For example, if I am willing to trade a few cycles of over head (redirect processing) for a simpler overall solution then I should be to do that. Fast path with XDP is still faster than the full host stack for known unicast traffic.