On 2018-07-26 19:45, Toke Høiland-Jørgensen wrote:
Wen Gong <wg...@codeaurora.org> writes:

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.

When I tested this, a pacing shift of 8 was quite close to optimal as
well for ath10k. Why are you getting different results?

the default value is still 8 in the patch:
https://patchwork.kernel.org/patch/10545361/

In my test, pacing shift 6 is better than 8.
The test is for ath10k/11AC WiFi chips.
Test result is show in the commit logs before.

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

Your tests do not include latency values; please try running a test that
also measures latency. The tcp_nup test in Flent (https://flent.org)
will do that, for instance. Also, is this a single TCP flow?


It is not a single TCP flow, it is 500Mbps with 5 flows.

below is result show in commit log before:
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

-Toke

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