Wen Gong [off-list ref] writes:

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-----Original Message-----
From: ath10k <redacted> On Behalf Of Toke
H=C3=B8iland-J=C3=B8rgensen
Sent: Wednesday, August 8, 2018 6:44 PM
To: Wen Gong <redacted>; ath10k@lists.infradead.org;
johannes@sipsolutions.net
Cc: linux-wireless@vger.kernel.org
Subject: Re: [PATCH v2 2/2] ath10k: Set sk_pacing_shift to 6 for 11AC Wi=

Fi

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chips
=20
Wen Gong [off-list ref] writes:
=20

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Upstream kernel has an interface to help adjust sk_pacing_shift to
help improve TCP UL throughput.
The sk_pacing_shift is 8 in mac80211, this is based on test with 11N
WiFi chips with ath9k. For QCA6174/QCA9377 PCI 11AC chips, the 11AC
VHT80 TCP UL throughput testing result shows 6 is the optimal.
Overwrite the sk_pacing_shift to 6 in ath10k driver for QCA6174/9377 P=

CI.

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Tested with QCA6174 PCI with firmware
WLAN.RM.4.4.1-00109-QCARMSWPZ-1, but this will also affect QCA9377

PCI.

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It's not a regression with new firmware releases.

There have 2 test result of different settings:

ARM CPU based device with QCA6174A PCI with different
sk_pacing_shift:

 sk_pacing_shift  throughput(Mbps)             CPU utilization
         6            500(-P5)      ~75% idle, Focus on CPU1: ~14%idle
         7            454(-P5)      ~80% idle, Focus on CPU1: ~4%idle
         8               288        ~90% idle, Focus on CPU1: ~35%idle
         9              ~200        ~92% idle, Focus on CPU1: ~50%idle

5G TCP UL VTH80 on X86 platform with QCA6174A PCI with
sk_packing_shift set to 6:

  tcp_limit_output_bytes            throughput(Mbps)
 default(262144)+1 Stream                 336
 default(262144)+2 Streams                558
 default(262144)+3 Streams                584
 default(262144)+4 Streams                602
 default(262144)+5 Streams                598
 changed(2621440)+1 Stream                598
 changed(2621440)+2 Streams               601

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You still haven't provided any latency numbers for these tests, which ma=

kes

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it impossible to verify that setting sk_pacing_shift to 6 is the right t=

radeoff.

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=20
As I said before, from your numbers I suspect the right setting is actua=

lly 7,

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which would be 10-20ms less latency under load; way more important than
~50 Mbps...
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Hi Toke,
Could you give the command line for the latency test?
https://flent.org/intro.html#quick-start
I used the command but test failed:
flent tcp_download -p 1 -l 60 -H 192.168.1.5 -t text-to-be-included-in-pl=

ot -o file1.png

error loading plotter: unable to find plot configuration "1"

Try something like:


flent -H 192.168.1.5 -t "sk_pacing_shift 7" tcp_nup --test-parameter upload=
_streams=3D1


This will note the value of sk_pacing_shift you are testing in the data
file (so change that as appropriate), and you can vary the number of TCP
streams by changing the upload_streams parameter.

Note that in this case I'm assuming you are running Flent on the device
with the kernel you are trying to test, so you want a TCP transfer going
*from* the device. If not, change "tcp_nup" to "tcp_ndown" and
"upload_streams" to "download_streams". Upload is netperf TCP_STREAM
test, and download is TCP_MAERTS.

When running the above command you'll get a summary output on the
terminal that you can paste on the list; and also a data file to plot
things form. For instance, you can do something like 'flent -p ping_cdf
*.flent.gz' to get a CDF plot of all your test results afterwards. You
are also very welcome to send me the .flent.gz data files and I'll take
a look to make sure everything looks reasonable :)

-Toke