[SOLVED] ~90ms Jitter of realtek b851 onboard network card

xade93 · 2025-05-05 13:10:56

Symptom:
On my newly bought desktop computer there are jitters when playing Dota 2 using onboard wifi network (1 ~ 90ms so hardly noticeable via other means but very noticeable in game), which completely disappear if I connect to Internet via USB tethered phone (<5 ms), while connecting to the very same wifi.

Diagnose done:
Ran mtr to 8.8.8.8, high stdev.
Since
1. this completely disappears when I use usb tether to bypass my network card
2. mtr stdev is cumulative, and even to _gateway has high stdev

issue is likely in my network stack (driver + chip). Or very unlikely, it could also be something in router.

Apotheosis (192.168.0.42) -> 8.8.8.8 (8.8.8.8)                                                  2025-05-05T21:15:47+0800
Keys:  Help   Display mode   Restart statistics   Order of fields   quit
                                                                                Packets               Pings
 Host                                                                         Loss%   Snt   Last   Avg  Best  Wrst StDev
 1. _gateway                                                                   0.3%   330    0.7   1.6   0.3  82.4   5.8
 2. 100.66.0.3                                                                 1.2%   330    2.0   3.1   1.2 109.9   9.5
 3. chj-dsl9.vqbn.com                                                          0.3%   330    2.0   3.3   1.3  95.3   8.5
 4. 132.147.112.109                                                            0.0%   329    2.6   4.0   1.7 102.8   9.4
 5. 132.147.112.194                                                           24.0%   329    4.7   7.9   3.4 127.1  16.0
 6. 209.85.255.97                                                              0.0%   329    2.5   3.5   1.6 131.1   8.6
 7. 142.251.241.1                                                              0.0%   329    2.4   3.4   2.0 109.7   7.3
 8. dns.google                                                                 0.0%   329    2.8   3.0   1.5 105.9   7.2

Device info:

% lspci | awk '/[Nn]et/ {print $1}' | xargs -i% lspci -ks %
07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet Controller (rev 15)
	DeviceName: Realtek RTL8125BG LAN
	Subsystem: ASUSTeK Computer Inc. Onboard RTL8111H Ethernet
	Kernel driver in use: r8169
	Kernel modules: r8169
08:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device b851
	Subsystem: AzureWave Device 6110
	Kernel driver in use: rtw89_8851be
	Kernel modules: rtw89_8851be

% uname -r
6.14.4-arch1-1

Last edited by xade93 (2025-05-06 14:05:01)

seth · 2025-05-05 15:01:27

No problems w/ the RTL8125BG ?

Any signs of roaming in the journal?

Try to disable the power saving stuff:

rtw89_pci.disable_clkreq=y rtw89_pci.disable_aspm_l1=y rtw89_pci.disable_aspm_l1ss=y

https://wiki.archlinux.org/title/Kernel_parameters

xade93 · 2025-05-05 15:48:52

seth wrote:

No problems w/ the RTL8125BG ?
Any signs of roaming in the journal?
Try to disable the power saving stuff:
rtw89_pci.disable_clkreq=y rtw89_pci.disable_aspm_l1=y rtw89_pci.disable_aspm_l1ss=y
https://wiki.archlinux.org/title/Kernel_parameters

1. I have no mean to test the wired card at the moment, will try to find a way and report back
2. No. Below is taken after a series of successful spot of jitter

% sudo journalctl -k | grep -E 'roam|assoc|disassoc|deauth'
May 05 23:41:34 Apotheosis kernel: wlp8s0: associate with 74:05:a5:75:20:c7 (try 1/3)
May 05 23:41:34 Apotheosis kernel: wlp8s0: associated

3. Inserted, verified below, still have jitter

[root@Apotheosis xade]# cat /proc/cmdline
initrd=\initramfs-linux.img root=UUID=fad64a21-7e04-427d-b344-e60c609a9d43 rtw89_pci.disable_clkreq=y rtw89_pci.disable_aspm_l1=y rtw89_pci.disable_aspm_l1ss=y

I kinda suspect it's the "AzureWave Device 6110" thingy ... did not find documentation online about its compatibility on Linux.

Last edited by xade93 (2025-05-05 15:52:51)

seth · 2025-05-06 07:33:09

Is it a 5GHz or 2.4GHz connection? Any chance for interference (eg. from bluetooth)?

xade93 · 2025-05-06 12:47:48

1. It is 5GHz originally, to separate issue I tried the 2.4GHz counterpart, issue persists

sudo iw dev wlp8s0 link
Connected to 74:05:a5:75:20:c7 (on wlp8s0)
	SSID: sus
	freq: 5785.0
	RX: 86543 bytes (205 packets)
	TX: 39484 bytes (194 packets)
	signal: -40 dBm
	rx bitrate: 390.0 MBit/s VHT-MCS 9 80MHz VHT-NSS 1
	tx bitrate: 433.3 MBit/s VHT-MCS 9 80MHz short GI VHT-NSS 1
	bss flags: short-slot-time
	dtim period: 1
	beacon int: 100

2. Bluetooth is soft-blocked in rfkill

% rfkill list
0: hci0: Bluetooth
	Soft blocked: yes
	Hard blocked: no
1: phy0: Wireless LAN
	Soft blocked: no
	Hard blocked: no

xade93 · 2025-05-06 14:04:23

Huh. After upgrading system again (last update just 7 days ago), this issue thats bothering me for 3 month went away. Huh.

[2025-04-30T21:42:40+0800] [ALPM] upgraded linux-api-headers (6.13-1 -> 6.14-1)
[2025-04-30T21:43:17+0800] [ALPM] upgraded linux (6.13.8.arch1-1 -> 6.14.4.arch1-1)
[2025-04-30T21:43:17+0800] [ALPM] upgraded linux-firmware-whence (20250311.b69d4b74-3 -> 20250408.c1a774f3-1)
[2025-04-30T21:43:18+0800] [ALPM] upgraded linux-firmware (20250311.b69d4b74-3 -> 20250408.c1a774f3-1)
[2025-04-30T21:43:20+0800] [ALPM] upgraded linux-headers (6.13.8.arch1-1 -> 6.14.4.arch1-1)
[2025-05-06T20:59:15+0800] [ALPM] upgraded linux (6.14.4.arch1-1 -> 6.14.4.arch1-2)
[2025-05-06T20:59:17+0800] [ALPM] upgraded linux-headers (6.14.4.arch1-1 -> 6.14.4.arch1-2)

seth · 2025-05-06 15:18:46

Do you get it w/ the LTS kernel?
Do you still ahve the rtw89_pci parameters in place?

Arch Linux

#1 2025-05-05 13:10:56

[SOLVED] ~90ms Jitter of realtek b851 onboard network card

#2 2025-05-05 15:01:27

Re: [SOLVED] ~90ms Jitter of realtek b851 onboard network card

#3 2025-05-05 15:48:52

Re: [SOLVED] ~90ms Jitter of realtek b851 onboard network card

#4 2025-05-06 07:33:09

Re: [SOLVED] ~90ms Jitter of realtek b851 onboard network card

#5 2025-05-06 12:47:48

Re: [SOLVED] ~90ms Jitter of realtek b851 onboard network card

#6 2025-05-06 14:04:23

Re: [SOLVED] ~90ms Jitter of realtek b851 onboard network card

#7 2025-05-06 15:18:46

Re: [SOLVED] ~90ms Jitter of realtek b851 onboard network card

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