AR# 75195

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2020.1 Zynq-7000: Ethernet Performance Numbers Lower in Linux 5.4 kernel

Description

There is a performance drop of 100 to 150 Mbps on the TX and RX side on Zynq-7000 devices for both PS and PL Ethernet when comparing performance testing between the 2019.2 and 2020.1 releases.

Solution

This is a known issue in the 2020.1 release Linux 5.4 kernel which affects Zynq-7000 devices only.

Zynq UltraScale+ MPSoC/RFSoC and Versal devices are not affected.

Currently there is no solution for this performance drop, but if users need to they can revert to the patch below.

https://github.com/Xilinx/linux-xlnx/commit/ac7c3e4ff401b304489a031938dbeaab585bfe0a


Root Cause:
The drop is due to the "enable CONFIG_OPTIMIZE_INLINING forcibly" commit in the Linux Kernel.

The Kernel and networking stack has a large number of inline functions, so an unoptimized inline function could be leading to a performance drop (this could also be dependent on the GCC version) .


The performance drop is observed on GEM and Xilinx AXI Ethernet MACs on Zynq-7000 devices only.

Xilinx is working to document the performance drop and initiate the discussion with the mainline community so that it is analyzed by the respective kernel maintainers.

Attachments

Associated Attachments

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
73686 PetaLinux 2020.1 - Product Update Release Notes and Known Issues N/A N/A
AR# 75195
Date 07/14/2020
Status Active
Type Known Issues
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