From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.toke.dk ([52.28.52.200]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gwrMC-0008Sk-9c for ath10k@lists.infradead.org; Thu, 21 Feb 2019 16:37:58 +0000 From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= Subject: Re: [PATCH v2 2/2] ath10k: Set sk_pacing_shift to 6 for 11AC WiFi chips In-Reply-To: References: <1533724802-30944-1-git-send-email-wgong@codeaurora.org> <1533724802-30944-3-git-send-email-wgong@codeaurora.org> <87sh3pdtpg.fsf@toke.dk> <87mutue4y8.fsf@toke.dk> <1535967508.3437.31.camel@sipsolutions.net> <87in3m25uu.fsf@toke.dk> <1535975240.3437.61.camel@sipsolutions.net> <878t4i1z74.fsf@toke.dk> <871sa7ylmi.fsf@toke.dk> <87r2c1i1vj.fsf@toke.dk> <871s41nmvx.fsf@kamboji.qca.qualcomm.com> Date: Thu, 21 Feb 2019 17:37:53 +0100 Message-ID: <87ftshhzby.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: Ben Greear , Kalle Valo Cc: Kan Yan , wgong@qti.qualcomm.com, linux-wireless@vger.kernel.org, ath10k@lists.infradead.org, Grant Grundler , wgong@codeaurora.org, Johannes Berg QmVuIEdyZWVhciA8Z3JlZWFyYkBjYW5kZWxhdGVjaC5jb20+IHdyaXRlczoKCj4gT24gMi8yMS8x OSA4OjEwIEFNLCBLYWxsZSBWYWxvIHdyb3RlOgo+PiBUb2tlIEjDuGlsYW5kLUrDuHJnZW5zZW4g PHRva2VAdG9rZS5kaz4gd3JpdGVzOgo+PiAKPj4+IEdyYW50IEdydW5kbGVyIDxncnVuZGxlckBn b29nbGUuY29tPiB3cml0ZXM6Cj4+Pgo+Pj4+IE9uIFRodSwgU2VwIDYsIDIwMTggYXQgMzoxOCBB TSBUb2tlIEjDuGlsYW5kLUrDuHJnZW5zZW4gPHRva2VAdG9rZS5kaz4gd3JvdGU6Cj4+Pj4+Cj4+ Pj4+IEdyYW50IEdydW5kbGVyIDxncnVuZGxlckBnb29nbGUuY29tPiB3cml0ZXM6Cj4+Pj4+Cj4+ Pj4+Pj4gQW5kLCB3ZWxsLCBHcmFudCdzIGRhdGEgaXMgZnJvbSBhIHNpbmdsZSB0ZXN0IGluIGEg bm9pc3kKPj4+Pj4+PiBlbnZpcm9ubWVudCB3aGVyZSB0aGUgdGltZSBzZXJpZXMgZ3JhcGggc2hv 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aGVpciB1c2UKPiBjYXNlLgoKV2VsbCBpZiBUQ1AgaXMgYnJva2VuIHRvIHRoZSBwb2ludCBvZiBi ZWluZyB1bnVzYWJsZSBJIGRvIHRoaW5rIHdlCnNob3VsZCBmaXggaXQ7IGJ1dCBJIHRoaW5rICJq dXN0IHByb3ZpZGUgYSBjb25maWd1cmF0aW9uIGtub2IiIHNob3VsZCBiZQp0aGUgbGFzdCByZXNv cnQuLi4KCi1Ub2tlCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fXwphdGgxMGsgbWFpbGluZyBsaXN0CmF0aDEwa0BsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6 Ly9saXN0cy5pbmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vYXRoMTBrCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC465C43381 for ; Thu, 21 Feb 2019 16:37:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8936B2083B for ; Thu, 21 Feb 2019 16:37:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=toke.dk header.i=@toke.dk header.b="gn5sGb9V" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726344AbfBUQhz (ORCPT ); Thu, 21 Feb 2019 11:37:55 -0500 Received: from mail.toke.dk ([52.28.52.200]:58383 "EHLO mail.toke.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725767AbfBUQhz (ORCPT ); Thu, 21 Feb 2019 11:37:55 -0500 From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1550767073; bh=aoMjcOS2+u4QXHdpGGrxL0br5vR83sXLCT2ccGpK37g=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=gn5sGb9VAptEF+PoQAi5vNPGl5g6AeWkwazidxar3/LfkJEUVnFg1ALs/zlbgkSfS DpiFOYyMUEqF+rqFW7cHpb0waROLDlTjjb3k5GkWK55dA87HdH2ooHpYYnQ6CumcZ0 TVcNYV3X0jO6ny2aqNyOQyOEmC8UeWnQqtYUaHNahQOcuusAzP7MDu8X26jcK7jj7V LNoiAP9Hg4omleblWwzCApv3X0CSUHFUXlOAQV4YnExAkpUSh56e38o/epMpuGaxfy tcl3crO69XxFHd5yFqHN4Ae8sAcFEmfLOP9M+S84/uqMwcM7H0vGvzP/i0ztbhp9lL iv+Pds+sYLw5w== To: Ben Greear , Kalle Valo Cc: Grant Grundler , Kan Yan , linux-wireless@vger.kernel.org, Johannes Berg , wgong@qti.qualcomm.com, ath10k@lists.infradead.org, wgong@codeaurora.org Subject: Re: [PATCH v2 2/2] ath10k: Set sk_pacing_shift to 6 for 11AC WiFi chips In-Reply-To: References: <1533724802-30944-1-git-send-email-wgong@codeaurora.org> <1533724802-30944-3-git-send-email-wgong@codeaurora.org> <87sh3pdtpg.fsf@toke.dk> <87mutue4y8.fsf@toke.dk> <1535967508.3437.31.camel@sipsolutions.net> <87in3m25uu.fsf@toke.dk> <1535975240.3437.61.camel@sipsolutions.net> <878t4i1z74.fsf@toke.dk> <871sa7ylmi.fsf@toke.dk> <87r2c1i1vj.fsf@toke.dk> <871s41nmvx.fsf@kamboji.qca.qualcomm.com> Date: Thu, 21 Feb 2019 17:37:53 +0100 X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <87ftshhzby.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Ben Greear writes: > On 2/21/19 8:10 AM, Kalle Valo wrote: >> Toke H=C3=B8iland-J=C3=B8rgensen writes: >>=20 >>> Grant Grundler writes: >>> >>>> On Thu, Sep 6, 2018 at 3:18 AM Toke H=C3=B8iland-J=C3=B8rgensen wrote: >>>>> >>>>> Grant Grundler writes: >>>>> >>>>>>> And, well, Grant's data is from a single test in a noisy >>>>>>> environment where the time series graph shows that throughput is al= l over >>>>>>> the place for the duration of the test; so it's hard to draw solid >>>>>>> conclusions from (for instance, for the 5-stream test, the average >>>>>>> throughput for 6 is 331 and 379 Mbps for the two repetitions, and f= or 7 >>>>>>> it's 326 and 371 Mbps) . Unfortunately I don't have the same hardwa= re >>>>>>> used in this test, so I can't go verify it myself; so the only thin= g I >>>>>>> can do is grumble about it here... :) >>>>>> >>>>>> It's a fair complaint and I agree with it. My counter argument is the >>>>>> opposite is true too: most ideal benchmarks don't measure what most >>>>>> users see. While the data wgong provided are way more noisy than I >>>>>> like, my overall "confidence" in the "conclusion" I offered is still >>>>>> positive. >>>>> >>>>> Right. I guess I would just prefer a slightly more comprehensive >>>>> evaluation to base a 4x increase in buffer size on... >>>> >>>> Kalle, is this why you didn't accept this patch? Other reasons? >>>> >>>> Toke, what else would you like to see evaluated? >>>> >>>> I generally want to see three things measured when "benchmarking" >>>> technologies: throughput, latency, cpu utilization >>>> We've covered those three I think "reasonably". >>> >>> Hmm, going back and looking at this (I'd completely forgotten about this >>> patch), I think I had two main concerns: >>> >>> 1. What happens in a degraded signal situation, where the throughput is >>> limited by the signal conditions, or by contention with other devic= es. >>> Both of these happen regularly, and I worry that latency will be >>> badly affected under those conditions. >>> >>> 2. What happens with old hardware that has worse buffer management in >>> the driver->firmware path (especially drivers without push/pull mode >>> support)? For these, the lower-level queueing structure is less >>> effective at controlling queueing latency. >>=20 >> Do note that this patch changes behaviour _only_ for QCA6174 and QCA9377 >> PCI devices, which IIRC do not even support push/pull mode. All the >> rest, including QCA988X and QCA9984 are unaffected. > > Just as a note, at least kernels such as 4.14.whatever perform poorly when > running ath10k on 9984 when acting as TCP endpoints. This makes them not > really usable for stuff like serving video to lots of clients. > > Tweaking TCP (I do it a bit differently, but either way) can significantly > improve performance. Differently how? Did you have to do more than fiddle with the pacing_shift? > Recently I helped a user that could get barely 70 stations streaming > at 1Mbps on stock kernel (using one wave1 on 2.4, one wave-2 on 5Ghz), > and we got 110 working with a tweaked TCP stack. These were /n > stations too. > > I think it is lame that it _still_ requires out of tree patches to > make TCP work well on ath10k...even if you want to default to current > behaviour, you should allow users to tweak it to work with their use > case. Well if TCP is broken to the point of being unusable I do think we should fix it; but I think "just provide a configuration knob" should be the last resort... -Toke