Very Slow upload speed | Ubuntu 16.04 | Dual-boot | Qualcomm Atheros QCA6174 802.11ac Wireless Network Adapter [168c:003e]

You appear to be effected by this bug. There are 68 posts of problems and suggestions. The latest one suggests to:

• Disable power saving
• Use latest kernel version - I'm using 4.14.34 and have had no problems on the 4.14 chain which is LTS (Long Term Support) for 6 years.

May 4, 2019 update

Over a year ago, but after the original answer was posted, a bug fix came out. It happened during the kernel 4.16-rc5 release and the source code change comments state:

Achieved throughput for different values of sk_pacing_shift (average of 5 iterations of 10-sec netperf runs to a host on the other side of the WiFi hop):

• sk_pacing_shift 10: 43.21 Mbps (pre-patch)
• sk_pacing_shift 9: 78.17 Mbps
• sk_pacing_shift 8: 123.94 Mbps
• sk_pacing_shift 7: 128.31 Mbps

Latency for competing flows increases from ~3 ms to ~10 ms with this change. This is about the same magnitude of queueing latency induced by flows that are not originated on the WiFi device itself (and so are not limited by TSQ).

Signed-off-by: Toke Høiland-Jørgensen

Instinctively you think a kernel greater than 4.15 is required to get the bug fix. This is not so as the next section explains.

Kernel 4.16-rc5 through Kernel 5.0 bug fixes are in 4.14.114 LTS

I'm still on kernel 4.14.xxx LTS (Long Term Support) which has another 5 years of updates coming for it including the 4.16 patch above and recent kernel 5.0 bug fixes.

To prove the bug fix is there go to where my current kernel 4.14.114 is:

• https://kernel.ubuntu.com/~kernel-ppa/mainline/v4.14.114/

It says:

To obtain the source from which they are built fetch the commit below:

git://git.launchpad.net/~ubuntu-kernel-test/ubuntu/+source/linux/+git/mainline-crack v4.14.114

• Copy and paste the address into your web browser and press Enter
• Google search comes up
• Click the first link
• A web page appears: https://code.launchpad.net/~ubuntu-kernel-test/ubuntu/+source/linux/+git/mainline-crack/+ref/master
• Scroll to the bottom and select All commits
• The commit we are looking for is 10,000 messages back which is a lot of scrolling and searching.
• To speed the process up type Adjust TSQ pacing shift into the search field.
• An abbreviated result appears so click Expand and you will see:

I can confirm this issue is related to bug #1670041 as @WinEunuuchs2Unix posted. FYI, my PCI-E wireless adapter is TP-LINK TL-WDN4800:

lspci -nn |grep -i wireless

Network controller [0280]: Qualcomm Atheros AR93xx Wireless Network Adapter [168c:0030] (rev 01)

The low throughput with transmit TCP streams on ath10k should be fixed with this mac80211 commit:

mac80211: Adjust TSQ pacing shift

https://git.kernel.org/linus/36148c2bbfbe50c50206b6f61d072203c80161e0

Apparently v4.16-rc5 was the first release to have that commit.

Upgrading my kernel to 4.17 (former is 4.14 LTS) fixes this.