Bug 105471

Summary:	10ec:8176 rtl8192ce 200-3200+ms latency on 802.11n 2.4GHz network with no load
Product:	Networking	Reporter:	Chris Peñalver (chris)
Component:	Wireless	Assignee:	networking_wireless (networking_wireless)
Status:	RESOLVED CODE_FIX
Severity:	high	CC:	chaoming_li, Larry.Finger, szg00000
Priority:	P1
Hardware:	x86-64
OS:	Linux
URL:	https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1445840
Kernel Version:	4.3.0-rc3-wl	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	info.txt Patch to change delays to sleeps

Description Chris Peñalver 2015-10-04 23:30:22 UTC

Created attachment 189441 [details]
info.txt

[1.] One line summary of the problem:
10ec:8176 rtl8192ce 200-3200+ms latency on 802.11n 2.4GHz network with no load

[2.] Full description of the problem/report:
This is a follow up to http://marc.info/?l=linux-wireless&m=143264578518617&w=2 . With an Asus PCE-N10 PCI-E Adapter Wireless N card (10ec:8176 rtl8192ce) I have 200-3200+ms latency on a 802.11n 2.4GHz network pinging just the gateway 192.168.1.1, with no network load on either the router or the WiFi chipset. The computer is ~4 feet away from a Verizon Jetpack MiFi 5510L with latest firmware installed (L1.34.23 M1.34.20) connected to a power source, with no obstructions between them. Other clients (same version of latest upstream kernel+Ubuntu with different chipset, Windows) don't have this problem.

For example, transferring data to a Windows 8.1 laptop, I obtain ~250Kbps. However, my other laptops consistently transfer to it at 1.5 Mbps.

I've tested both latest mainline (4.3-rc3) and wireless-testing branch as per https://wireless.wiki.kernel.org/en/developers/documentation/git-guide and it's the same old story.

Please see attached info.txt for full debug information.

Comment 1 Chris Peñalver 2015-12-15 13:09:46 UTC

This device works flawlessly (i.e. never above 30ms on pings for hours) both in Windows 8.1, and Windows 10. Hence, this is a clearcut upstream linux driver problem.

Comment 2 Larry Finger 2016-02-16 16:41:36 UTC

Created attachment 203741 [details]
Patch to change delays to sleeps

With this patch, which has been pushed upstream, my typical ping results are

rtt min/avg/max/mdev = 1.302/4.134/101.955/10.126 ms

Although that max is greater than what you see for Windows, it seems to be an improvement.

If possible, please test and report your results.

Comment 3 Chris Peñalver 2016-02-16 17:39:31 UTC

Larry Finger, thanks for your hard work towards this.

Given you have confirmed an improvement, and it was submitted upstream, I'll close this report as fixed.

Please adjust the Status if inappropriate.