netdev - Re: [PATCH RFC net-next 1/2] net: Reference bpf_redirect_info via task_struct on PREEMPT

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Message-ID: <20240216165737.oIFG5g-U@linutronix.de>
Date: Fri, 16 Feb 2024 17:57:37 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Toke Høiland-Jørgensen <toke@...hat.com>
Cc: Jesper Dangaard Brouer <hawk@...nel.org>, bpf@...r.kernel.org,
	netdev@...r.kernel.org,
	Björn Töpel <bjorn@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Alexei Starovoitov <ast@...nel.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Eric Dumazet <edumazet@...gle.com>, Hao Luo <haoluo@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	Jonathan Lemon <jonathan.lemon@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
	Magnus Karlsson <magnus.karlsson@...el.com>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Paolo Abeni <pabeni@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>, Song Liu <song@...nel.org>,
	Stanislav Fomichev <sdf@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Yonghong Song <yonghong.song@...ux.dev>
Subject: Re: [PATCH RFC net-next 1/2] net: Reference bpf_redirect_info via
 task_struct on PREEMPT_RT.

On 2024-02-15 21:23:23 [+0100], Toke Høiland-Jørgensen wrote:
> The tricky part is that the traffic actually has to stress the CPU,
> which means that the offered load has to be higher than what the CPU can
> handle. Which generally means running on high-speed NICs with small
> packets: a modern server CPU has no problem keeping up with a 10G link
> even at 64-byte packet size, so a 100G NIC is needed, or the test needs
> to be run on a low-powered machine.

I have 10G box. I can tell cpufreq to go down to 1.1Ghz and I could
reduce the queues to one and hope that it is slow enough.

> As a traffic generator, the xdp-trafficgen utility also in xdp-tools can
> be used, or the in-kernel pktgen, or something like T-rex or Moongen.
> Generally serving UDP traffic with 64-byte packets on a single port
> is enough to make sure the traffic is serviced by a single CPU, although
> some configuration may be needed to steer IRQs as well.

I played with xdp-trafficgen:
| # xdp-trafficgen udp eno2  -v
| Current rlimit is infinity or 0. Not raising
| Kernel supports 5-arg xdp_cpumap_kthread tracepoint
| Error in ethtool ioctl: Operation not supported
| Got -95 queues for ifname lo
| Kernel supports 5-arg xdp_cpumap_kthread tracepoint
| Got 94 queues for ifname eno2
| Transmitting on eno2 (ifindex 3)
| lo->eno2                        0 err/s                 0 xmit/s
| lo->eno2                        0 err/s                 0 xmit/s
| lo->eno2                        0 err/s                 0 xmit/s

I even tried set the MAC address with -M/ -m but nothing happens. I see
and on drop side something happening when I issue a ping command.
Does something ring a bell? Otherwise I try the pktgen. This is a Debian
kernel (just to ensure I didn't break something or forgot a config
switch).

> -Toke

Sebastian