netdev - Re: XDP Performance Regression in recent kernel versions

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Message-ID: <36075ea9-95dd-4dd6-b2b6-440916079578@nvidia.com>
Date: Wed, 19 Jun 2024 09:00:03 +0300
From: Tariq Toukan <tariqt@...dia.com>
To: Sebastiano Miano <mianosebastiano@...il.com>, bpf@...r.kernel.org,
 netdev@...r.kernel.org
Cc: saeedm@...dia.com, tariqt@...dia.com, hawk@...nel.org,
 edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
 Gal Pressman <gal@...dia.com>, amira@...dia.com
Subject: Re: XDP Performance Regression in recent kernel versions


On 18/06/2024 18:28, Sebastiano Miano wrote:
> Hi folks,
> 
> I have been conducting some basic experiments with XDP and have
> observed a significant performance regression in recent kernel
> versions compared to v5.15.
> 

Hi,

> My setup is the following:
> - Hardware: Two machines connected back-to-back with 100G Mellanox
> ConnectX-6 Dx.
> - DUT: 2x16 core Intel(R) Xeon(R) Silver 4314 CPU @ 2.40GHz.
> - Software: xdp-bench program from [1] running on the DUT in both DROP
> and TX modes.
> - Traffic generator: Pktgen-DPDK sending traffic with a single 64B UDP
> flow at ~130Mpps.
> - Tests: Single core, HT disabled
> 
> Results:
> 
> Kernel version |-------| XDP_DROP |--------|   XDP_TX  |
> 5.15                                30Mpps                  16.1Mpps
> 6.2                                21.3Mpps                 14.1Mpps
> 6.5                                19.9Mpps                  8.6Mpps
> bpf-next (6.10-rc2)        22.1Mpps                 9.2Mpps
> 
> I repeated the experiments multiple times and consistently obtained
> similar results.
> Are you aware of any performance regressions in recent kernel versions
> that could explain these results?
> 
> [1] https://github.com/xdp-project/xdp-tools
> 

Thanks for your report.

I assume cpu util for the active core on the DUT is 100% in all cases, 
right?

Can you please share some more details? Like relevant ethtool counters, 
and perf top output.

We'll check if this repro for us as well.