[RFC Patch net-next v1 0/9] r8169: add RSS support for RTL8127

[javen <javen_xu@realsil.com.cn>]

From: Javen Xu <javen_xu@realsil.com.cn>

This series patch adds RSS support for RTL8127 in the r8169 driver.

Currently, without RSS support, a single CPU core handles all incoming
traffic. Under heavy loads, this single core becomes a bottleneck, causing
high softirq usage and leading to unstable and degraded network throughput.

As a result, we add rss support for RTL8127. This RFC patch is just for
discussing. And we do some experiments on AMD platform. Below is the 
result.

Platform: AMD Ryzen Embedded R2514 with Radeon Graphics(4 Cores/8 Threads)
Arch: x86_64
Test command: 
  Server: iperf3 -s
  Client: iperf3 -c 192.168.2.1 -P 20 -t 3600
Monitor: mpstat -P ALL 1

Before this patch (Without RSS):
  Throughput: Unstable, fluctuating between 3.76 Gbits/sec and
  8.2 Gbits/sec.
  CPU Usage: A single CPU core is fully occupied with softirq reaching 
  up to 96%.

After this patch (With RSS enabled):
  Throughput: Stable at 9.42 Gbits/sec.
  CPU Usage: The traffic load is evenly distributed across multiple CPU
  cores. The maximum softirq on a single core dropped to 63%.
  
Patch summary:
  Patch 1: Adds necessary macro and register definitions for RSS.
  Patch 2-4: Support NAPI and multi RX/TX queues.
  Patch 5-6: Support MSI-X and enables it specifically for RTL8127.
  Patch 7: Enables RSS for RTL8127.
  Patch 8-9: Adds ethtool support to configure the number of RX queues.
  
Javen Xu (9):
  r8169: add some register definitions
  r8169: add napi and irq support
  r8169: add support for multi tx queues
  r8169: add support for multi rx queues
  r8169: add support for msix
  r8169: enable msix for RTL8127
  r8169: add support and enable rss
  r8169: move struct ethtool_ops
  r8169: add support for ethtool

 drivers/net/ethernet/realtek/r8169_main.c | 1437 ++++++++++++++++++---
 1 file changed, 1238 insertions(+), 199 deletions(-)

-- 
2.43.0