Re: Poor wifi performance on Intel 7260 Dual-Band AC Wifi card

[Johannes Stezenbach <js@sig21.net>]

On Wed, Jul 30, 2014 at 01:08:30PM +0200, Johannes Stezenbach wrote:
> The question is how to go about testing.  ISTR the Windows 8 driver
> didn't have any issue and gave decent speed, but I don't have the
> time to restore the Windows image for testing now.  If Windows
> and Linux use the same firmware I guess a comparison would
> reveal if it's a driver of firmware issue.

I had some spare time today to restore the Windows 8 image
and test (praise Clonezilla!).  The test is with an AP which
(sometimes) sends broken beacons, so the result might not be viewed
as valid by some, but I'm just comparing performance of
different hardware and software under the same conditions.
https://bugzilla.kernel.org/show_bug.cgi?id=78101

Earlier today I could connect with Linux and the
Dual Band Wireless-AC 7260 gave me <50KB/s download
speed (fetching kernel tarball from PC connected via
1G ethernet to the AP).  An rt2800 usb dongle on the
same machine gave me ~2.5MB/s.  Currently Linux
cannot connect at all (see bug 78101) due to the
broken beacon.

With Windows 8 (Driver Version 16.10.0.5, Driver Date 1/28/2014)
I had no problems to connect, and got ~400KB/s download speed.
(I confirmed via capture on the PC that the beacons
were broken in the way described in bug 78101 during this test.)
The rt2800 usb dongle gave me 2.4MB/s in Windows.

I couldn't reboot the AP today to see if and how much
the performance improves when the beacons are not broken.
I'll do that when I have time.  In the past, rebooting
the AP did fix the connection issue (good beacon for some time),
but did not turn the AC 7260 into a speed demon with the
Linux driver.

The AP only supports 2.4Ghz band 802.11n.

> Otherwise I'm hoping Intel guys could provide some guidance for
> testing so we could find the root cause.

So far Intel did not show much interest in the issue, but
a laptop user often has no control on the AP (travelling,
hotels, conferences, etc.).  IMHO Intel would their users
a big favor if they spent some time optimizing for bad
network conditions.  The broken AP on my side will be
replaced soon, but that's not the point of my complaint.


Thanks,
Johannes