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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 A6272C3A5A7 for ; Wed, 4 Sep 2019 13:34:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B01422CEA for ; Wed, 4 Sep 2019 13:34:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730070AbfIDNeo (ORCPT ); Wed, 4 Sep 2019 09:34:44 -0400 Received: from mail.taht.net ([176.58.107.8]:59680 "EHLO mail.taht.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729626AbfIDNeo (ORCPT ); Wed, 4 Sep 2019 09:34:44 -0400 Received: from dancer.taht.net (unknown [IPv6:2603:3024:1536:86f0:eea8:6bff:fefe:9a2]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.taht.net (Postfix) with ESMTPSA id 71D9F22898; Wed, 4 Sep 2019 13:34:42 +0000 (UTC) From: Dave Taht To: Wen Gong Cc: "ath10k\@lists.infradead.org" , "linux-wireless\@vger.kernel.org" Subject: Re: [PATCH 2/7] ath10k: change max RX bundle size from 8 to 32 for sdio References: <1566302108-18219-1-git-send-email-wgong@codeaurora.org> <1566302108-18219-3-git-send-email-wgong@codeaurora.org> <87k1apnyyo.fsf@taht.net> <259d8d7f8c2a4c428ae14ff211c83c1a@aptaiexm02f.ap.qualcomm.com> Date: Wed, 04 Sep 2019 06:34:29 -0700 In-Reply-To: <259d8d7f8c2a4c428ae14ff211c83c1a@aptaiexm02f.ap.qualcomm.com> (Wen Gong's message of "Wed, 4 Sep 2019 04:43:21 +0000") Message-ID: <87lfv4chi2.fsf@taht.net> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Wen Gong writes: >> -----Original Message----- >> From: Dave Taht >> Sent: Wednesday, September 4, 2019 12:10 AM >> To: Wen Gong ; ath10k@lists.infradead.org; >> linux-wireless@vger.kernel.org >> Subject: [EXT] Re: [PATCH 2/7] ath10k: change max RX bundle size from 8 to >> 32 for sdio >> >> >> In terms of deeply grokking what increasing buffering to achieve high >> bandwidth on a testbench, vs what it can do to clobber latency in the >> real world at low bandwidths, I tend to point folk at: >> >> https://www.youtube.com/watch?v=Rb-UnHDw02o&t=25m40s >> >> where I got a whole bunch of hackers to stand up and act like packets >> in an aggregating FIFO wifi queue. >> >> This key section is only 8 minutes long, and I promise, y'all laugh >> at least 3 times at the demonstration. >> >> At the time, also, the ath10k was so overbuffered that on one test >> I could try to start 100 flows, and only get five. >> >> https://lwn.net/Articles/705884/ >> >> and on my slides: >> >> https://blog.linuxplumbersconf.org/2016/ocw//system/presentations/3963/ >> original/linuxplumbers_wifi_latency-3Nov.pdf >> > Hi Dave, > So your mean is change 8 to 32 will impact latency? It will increase latency of rx? Heh. for rx, in this case, probably not! I just get twitchy every time folk fiddle with buffer sizes. In one recent case someone had fiddled with the interrupt polling interval on something, going from 1ms to 10ms - it saved on cpu, but... ... just trying to make sure folk grok the tradoffs with a bit of laughter. carry on! > >> >> 0xFFFEFFFF