Low performance while accessing the server via xRDP

This document (000021159) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Desktop 15 all Service Packs
SUSE Linux Enterprise Desktop 12 SP5
SUSE Linux Enterprise Server 15 all Service Packs
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise for SAP Applications 15 all Service Packs
SUSE Linux Enterprise for SAP Applications 12 SP5

Situation

Remote desktop management has been enabled on the server using xRDP and accessed remotely with an RDP client like Vinagre or Remmina.

Screens are very slow to redraw, and general performance is very low while interacting with the remote server. This happens regardless of the available network bandwidth.

Resolution

Configure the TCP send buffer size

Edit the file /etc/xrdp/xrdp.ini
Locate the line that reads "tcp_send_buffer_bytes". Remove the comment character ("#").
Edit the value so it now reads:

tcp_send_buffer_bytes=4194304

Restart the service:

# systemctl restart xrdp

Configure the kernel network buffer size (optional)

Change the current network buffer size to a larger value with the following command:

sysctl -w net.core.wmem_max=8388608

Create a new file /etc/sysctl.d/xrdp.conf with the following content:

net.core.wmem_max = 8388608

This will ensure that the value is properly set between reboots.

Cause

The default TCP send buffer for xRDP is too small (32KB) to properly deal with current default monitor resolutions, like 1920x1080 and higher. This causes too much fragmentation on the xRDP protocol and consequent slow performance. By raising it to a sensible value (in this case, 4MB), the problem is solved.

Additional Information

We're also raising the kernel's maximum socket send buffers from the default 256KB to 820KB to minimize further TCP fragmentation. Please note that while this change will get better network performance for general networking tasks, it could affect the overall operation of the server in specific environments. Please consult your networking specialist to evaluate this change in your specific environment if problems arise.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

Document ID:000021159
Creation Date: 03-Aug-2023
Modified Date:08-Feb-2024
- SUSE Linux Enterprise Desktop
- SUSE Linux Enterprise Server
- SUSE Linux Enterprise Server for SAP Applications

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