XPost: linux.debian.bugs.dist 
 From: u.kleine-koenig@baylibre.com 
  
 Hello, 
  
 On Sun, Aug 17, 2025 at 01:49:17PM +0200, Andrea - wrote: 
 > Package: linux-image-6.12.0-1-amd64 
 > Version: 6.12.0-1 
 > Severity: important 
 > 
 > Hello, 
 > 
 > I am reporting a network performance regression with the Realtek RTL8125 
 > (PCI ID [10ec:8125]) when moving from Debian 12 (Bookworm, kernel 6.1 LTS) 
 > to Debian Trixie (kernel 6.12). 
 > 
 > - On Debian 12 with linux-image-6.1.0-26-amd64, throughput is ~838 Mb/s 
 >   on a gigabit Ethernet link (expected value). 
 > - On Debian 13 with linux-image-6.12.0-1-amd64, the link still negotiates 
 >   "Speed: 1000Mb/s, Duplex: Full" correctly, but actual throughput drops 
 >   to ~300 Mb/s. 
 > - I tested with both the in-kernel `r8169` driver and the external 
 >   `r8125-dkms` package (and also Realtek€€€s own source release). 
 >   The performance issue persists. 
  
 One possible culprit might be the energy saving option EEE. What is the 
 output of 
  
  ethtool --show-eee enp5s0 
  
 ? If this command reports EEE to be active, does 
  
  ethtool --set-eee enp5s0 eee off 
  
 fix the performance degration? 
  
 If that doesn't help, can you please provide a full kernel log (`sudo 
 journalctl -k` or `sudo dmesg`)? 
  
 Best regards 
 Uwe 
  
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