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From: Federico Parola <fede.parola@hotmail.it>
To: xdp-newbies@vger.kernel.org
Subject: Multi-core scalability problems
Date: Tue, 13 Oct 2020 15:49:03 +0200	[thread overview]
Message-ID: <VI1PR04MB3104C89EF8DCB98F5330F36C9E040@VI1PR04MB3104.eurprd04.prod.outlook.com> (raw)

Hello,
I'm testing the performance of XDP when dropping packets using multiple 
cores and I'm getting unexpected results.
My machine is equipped with a dual port Intel XL710 40 GbE and an Intel 
Xeon Gold 5120 CPU @ 2.20GHz with 14 cores (HyperThreading disabled), 
running Ubuntu server 18.04 with kernel 5.8.12.
I'm using the xdp_rxq_info program from the kernel tree samples to drop 
packets.
I generate 64 bytes UDP packets with MoonGen for a total of 42 Mpps. 
Packets are uniformly distributed in different flows (different src 
port) and I use flow direction rules on the rx NIC to send these flows 
to different queues/cores.
Here are my results:

1 FLOW:
Running XDP on dev:enp101s0f0 (ifindex:3) action:XDP_DROP options:no_touch
XDP stats       CPU     pps         issue-pps
XDP-RX CPU      0       17784270    0
XDP-RX CPU      total   17784270

RXQ stats       RXQ:CPU pps         issue-pps
rx_queue_index    0:0   17784270    0
rx_queue_index    0:sum 17784270
---

2 FLOWS:
Running XDP on dev:enp101s0f0 (ifindex:3) action:XDP_DROP options:no_touch
XDP stats       CPU     pps         issue-pps
XDP-RX CPU      0       7016363     0
XDP-RX CPU      1       7017291     0
XDP-RX CPU      total   14033655

RXQ stats       RXQ:CPU pps         issue-pps
rx_queue_index    0:0   7016366     0
rx_queue_index    0:sum 7016366
rx_queue_index    1:1   7017294     0
rx_queue_index    1:sum 7017294
---

4 FLOWS:
Running XDP on dev:enp101s0f0 (ifindex:3) action:XDP_DROP options:no_touch
XDP stats       CPU     pps         issue-pps
XDP-RX CPU      0       2359478     0
XDP-RX CPU      1       2358508     0
XDP-RX CPU      2       2357042     0
XDP-RX CPU      3       2355396     0
XDP-RX CPU      total   9430425

RXQ stats       RXQ:CPU pps         issue-pps
rx_queue_index    0:0   2359474     0
rx_queue_index    0:sum 2359474
rx_queue_index    1:1   2358504     0
rx_queue_index    1:sum 2358504
rx_queue_index    2:2   2357040     0
rx_queue_index    2:sum 2357040
rx_queue_index    3:3   2355392     0
rx_queue_index    3:sum 2355392

I don't understand why overall performance is reducing with the number 
of cores, according to [1] I would expect it to increase until reaching 
a maximum value. Is there any parameter I should tune to overcome the 
problem?

Thanks in advance for your help.
Federico Parola

[1] 
https://github.com/tohojo/xdp-paper/blob/master/benchmarks/bench02_xdp_drop.org

             reply	other threads:[~2020-10-13 13:49 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-13 13:49 Federico Parola [this message]
2020-10-13 16:41 ` Multi-core scalability problems Jesper Dangaard Brouer
2020-10-13 16:44 ` Toke Høiland-Jørgensen
2020-10-14  6:56   ` Federico Parola
2020-10-14  9:15     ` Jesper Dangaard Brouer
2020-10-14 12:17       ` Federico Parola
2020-10-14 14:26         ` Jesper Dangaard Brouer
2020-10-15 12:04           ` Federico Parola
2020-10-15 13:22             ` Jesper Dangaard Brouer
2020-10-19 15:23               ` Federico Parola
2020-10-19 18:26                 ` Jesper Dangaard Brouer
2020-10-24 13:57                   ` Federico Parola
2020-10-26  8:14                     ` Jesper Dangaard Brouer
     [not found] <VI1PR04MB3104C1D86BDC113F4AC0CF4A9E050@VI1PR04MB3104.eurprd04.prod.outlook.com>
2020-10-14  8:35 ` Federico Parola

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