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From: "Toke Høiland-Jørgensen" <toke@toke.dk>
To: Wen Gong <wgong@codeaurora.org>
Cc: ath10k@lists.infradead.org, johannes@sipsolutions.net,
	linux-wireless@vger.kernel.org
Subject: Re: [PATCH 2/2] ath10k: Set sk_pacing_shift to 6 for 11AC WiFi chips
Date: Fri, 27 Jul 2018 22:06:01 +0200	[thread overview]
Message-ID: <87h8kk1m1i.fsf@toke.dk> (raw)
In-Reply-To: <e5f8de75e2464393e8664d8bf913a827@codeaurora.org>

Wen Gong <wgong@codeaurora.org> writes:

> On 2018-07-26 19:45, Toke H=C3=B8iland-J=C3=B8rgensen wrote:
>> Wen Gong <wgong@codeaurora.org> writes:
>>=20
>>> Upstream kernel has an interface to help adjust sk_pacing_shift to=20
>>> 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.
>>=20
>> 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.
>>=20
>>> Tested with QCA6174 PCI with firmware
>>> WLAN.RM.4.4.1-00109-QCARMSWPZ-1, but this will also affect QCA9377=20
>>> PCI.
>>> It's not a regression with new firmware releases.
>>>=20
>>> There have 2 test result of different settings:
>>>=20
>>> ARM CPU based device with QCA6174A PCI with different
>>> sk_pacing_shift:
>>>=20
>>>  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
>>=20
>> Your tests do not include latency values; please try running a test=20
>> 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?
>>=20
>
> 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

This is useless without latency numbers. The whole point of
sk_pacing_shift is to control the tradeoff between latency and
throughput. You're only showing the throughput, so it's impossible to
judge if setting the pacing shift to 6 is right (and from your results I
suspect the sweet spot is actually 7).

-Toke

WARNING: multiple messages have this Message-ID
From: "Toke Høiland-Jørgensen" <toke@toke.dk>
To: Wen Gong <wgong@codeaurora.org>
Cc: johannes@sipsolutions.net, linux-wireless@vger.kernel.org,
	ath10k@lists.infradead.org
Subject: Re: [PATCH 2/2] ath10k: Set sk_pacing_shift to 6 for 11AC WiFi chips
Date: Fri, 27 Jul 2018 22:06:01 +0200	[thread overview]
Message-ID: <87h8kk1m1i.fsf@toke.dk> (raw)
In-Reply-To: <e5f8de75e2464393e8664d8bf913a827@codeaurora.org>

Wen Gong <wgong@codeaurora.org> writes:

> On 2018-07-26 19:45, Toke Høiland-Jørgensen wrote:
>> Wen Gong <wgong@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

This is useless without latency numbers. The whole point of
sk_pacing_shift is to control the tradeoff between latency and
throughput. You're only showing the throughput, so it's impossible to
judge if setting the pacing shift to 6 is right (and from your results I
suspect the sweet spot is actually 7).

-Toke

_______________________________________________
ath10k mailing list
ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k

  reply	other threads:[~2018-07-27 21:29 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-26  7:21 [PATCH 0/2] Change sk_pacing_shift in ieee80211_hw for best tx throughput Wen Gong
2018-07-26  7:21 ` Wen Gong
2018-07-26  7:21 ` [PATCH 1/2] mac80211: Save sk_pacing_shift to ieee80211_hw Wen Gong
2018-07-26  7:21   ` Wen Gong
2018-07-26 14:52   ` kbuild test robot
2018-07-26 14:52     ` kbuild test robot
2018-07-27  8:35     ` Wen Gong
2018-07-27  8:35       ` Wen Gong
2018-07-27  9:30       ` Kalle Valo
2018-07-27  9:30         ` Kalle Valo
2018-07-26  7:21 ` [PATCH 2/2] ath10k: Set sk_pacing_shift to 6 for 11AC WiFi chips Wen Gong
2018-07-26  7:21   ` Wen Gong
2018-07-26 11:45   ` Toke Høiland-Jørgensen
2018-07-26 11:45     ` Toke Høiland-Jørgensen
2018-07-26 13:02     ` Michał Kazior
2018-07-26 13:02       ` Michał Kazior
2018-07-27  9:39       ` Wen Gong
2018-07-27  9:39         ` Wen Gong
2018-07-27 12:33         ` Michał Kazior
2018-07-27 12:33           ` Michał Kazior
2018-07-27  9:29     ` Wen Gong
2018-07-27  9:29       ` Wen Gong
2018-07-27 20:06       ` Toke Høiland-Jørgensen [this message]
2018-07-27 20:06         ` Toke Høiland-Jørgensen
  -- strict thread matches above, loose matches on Subject: below --
2018-07-26  7:16 [PATCH 0/2] Change sk_pacing_shift in ieee80211_hw for best tx throughput Wen Gong
2018-07-26  7:16 ` [PATCH 2/2] ath10k: Set sk_pacing_shift to 6 for 11AC WiFi chips Wen Gong
2018-07-26  7:16   ` Wen Gong

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