From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.toke.dk ([2001:470:dc45:1000::1]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1fj90Z-0004AX-DN for ath10k@lists.infradead.org; Fri, 27 Jul 2018 20:06:42 +0000 From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= Subject: Re: [PATCH 2/2] ath10k: Set sk_pacing_shift to 6 for 11AC WiFi chips In-Reply-To: References: <1532589677-16428-1-git-send-email-wgong@codeaurora.org> <1532589677-16428-3-git-send-email-wgong@codeaurora.org> <87zhye1aqg.fsf@toke.dk> Date: Fri, 27 Jul 2018 22:06:01 +0200 Message-ID: <87h8kk1m1i.fsf@toke.dk> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "ath10k" Errors-To: ath10k-bounces+kvalo=adurom.com@lists.infradead.org To: Wen Gong Cc: johannes@sipsolutions.net, linux-wireless@vger.kernel.org, ath10k@lists.infradead.org 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rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389206AbeG0V3c (ORCPT ); Fri, 27 Jul 2018 17:29:32 -0400 From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Wen Gong 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 In-Reply-To: References: <1532589677-16428-1-git-send-email-wgong@codeaurora.org> <1532589677-16428-3-git-send-email-wgong@codeaurora.org> <87zhye1aqg.fsf@toke.dk> Date: Fri, 27 Jul 2018 22:06:01 +0200 Message-ID: <87h8kk1m1i.fsf@toke.dk> (sfid-20180727_220608_585232_8011BFDF) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: Wen Gong writes: > On 2018-07-26 19:45, Toke H=C3=B8iland-J=C3=B8rgensen wrote: >> Wen Gong 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