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=-10.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 3989CC433E2 for ; Mon, 31 Aug 2020 15:09:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D33A207EA for ; Mon, 31 Aug 2020 15:09:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728183AbgHaPI7 (ORCPT ); Mon, 31 Aug 2020 11:08:59 -0400 Received: from mga04.intel.com ([192.55.52.120]:31340 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728148AbgHaPI4 (ORCPT ); Mon, 31 Aug 2020 11:08:56 -0400 IronPort-SDR: PRx6sGSWTPBDkMdNq1Bu7dU6Ng2UE1P5G5czGu1x/t5U9dS6qgd6tSTJBs1Xnq1jI3ML1qXvwb g9yuWA/yt+mQ== X-IronPort-AV: E=McAfee;i="6000,8403,9730"; a="154395463" X-IronPort-AV: E=Sophos;i="5.76,376,1592895600"; d="scan'208";a="154395463" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2020 08:08:55 -0700 IronPort-SDR: FpZMj+8szrHvtzbhfmvek8LRdW5wMgZEh8InhUSTO3IOotFu7l7r9F9F27k5o8mkpPafnUBsVv lLKy3V4lYrCA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,376,1592895600"; d="scan'208";a="281671788" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.73]) ([10.237.72.73]) by fmsmga007.fm.intel.com with ESMTP; 31 Aug 2020 08:08:47 -0700 Subject: Re: Broadcom WiFi SDIO performance regression after commit "mmc: sdhci: Remove finish_tasklet" To: Dmitry Osipenko , Ulf Hansson , Arend van Spriel , Franky Lin , Hante Meuleman , Chi-Hsien Lin , Wright Feng , brcm80211-dev-list@cypress.com, brcm80211-dev-list.pdl@broadcom.com, "linux-tegra@vger.kernel.org" , linux-mmc , Linux Kernel Mailing List References: <5cf1af89-6026-09ad-7f20-82e19ad49fa1@gmail.com> <9332715c-6ee5-fce3-8b93-305823d5a551@intel.com> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: <379c7435-a940-c427-305d-c4fa5f1970d6@intel.com> Date: Mon, 31 Aug 2020 18:08:09 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/08/20 12:36 pm, Dmitry Osipenko wrote: > 27.08.2020 09:45, Adrian Hunter пишет: >> On 27/08/20 9:07 am, Dmitry Osipenko wrote: >>> Hello! >>> >>> I was debugging WiFi performance problems on Acer A500 tablet device >>> that has BCM4329 WiFi chip which is connected to NVIDIA Terga20 SoC via >>> SDIO and found that the following commit causes a solid 5-10 Mbit/s of >>> WiFi throughput regression after 5.2 kernel: >> >> What is that in percentage terms? > > That is about 20%. > >>> commit c07a48c2651965e84d35cf193dfc0e5f7892d612 >>> Author: Adrian Hunter >>> Date: Fri Apr 5 15:40:20 2019 +0300 >>> >>> mmc: sdhci: Remove finish_tasklet >>> >>> Remove finish_tasklet. Requests that require DMA-unmapping or >>> sdhci_reset >>> are completed either in the IRQ thread or a workqueue if the >>> completion is >>> not initiated by the IRQ. >>> >>> Reverting the offending commit on top of recent linux-next resolves the >>> problem. >>> >>> Ulf / Adrian, do you have any ideas what could be done in regards to >>> restoring the SDIO performance? Should we just revert the offending commit? >>> >> >> Unfortunately I think we are past the point of returning to the tasklet. >> >> sdhci can complete requests in the irq handler but only if ->pre_req() and >> ->post_req() are used, which is not supported by SDIO at present. pre_req >> and post_req were introduced to reduce latency for the block driver, so it >> seems reasonable perhaps to look at using them in SDIO as well. >> > > I'll try to take a look at pre/post_req(), but I'm not very familiar > with the MMC code, so it may take quite some time. Will be great if you > could help with making a patch that I could test! > You could start by seeing if using pre/post_req helps at all, as below. If that doesn't help, then it might need more analysis. diff --git a/drivers/mmc/core/sdio_ops.c b/drivers/mmc/core/sdio_ops.c index 93d346c01110..4c229dd2b6e5 100644 --- a/drivers/mmc/core/sdio_ops.c +++ b/drivers/mmc/core/sdio_ops.c @@ -121,6 +121,7 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, struct sg_table sgtable; unsigned int nents, left_size, i; unsigned int seg_size = card->host->max_seg_size; + int err; WARN_ON(blksz == 0); @@ -170,28 +171,32 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, mmc_set_data_timeout(&data, card); - mmc_wait_for_req(card->host, &mrq); + mmc_pre_req(card->host, &mrq); - if (nents > 1) - sg_free_table(&sgtable); + mmc_wait_for_req(card->host, &mrq); if (cmd.error) - return cmd.error; - if (data.error) - return data.error; - - if (mmc_host_is_spi(card->host)) { + err = cmd.error; + else if (data.error) + err = data.error; + else if (mmc_host_is_spi(card->host)) /* host driver already reported errors */ - } else { - if (cmd.resp[0] & R5_ERROR) - return -EIO; - if (cmd.resp[0] & R5_FUNCTION_NUMBER) - return -EINVAL; - if (cmd.resp[0] & R5_OUT_OF_RANGE) - return -ERANGE; - } + err = 0; + else if (cmd.resp[0] & R5_ERROR) + err = -EIO; + else if (cmd.resp[0] & R5_FUNCTION_NUMBER) + err = -EINVAL; + else if (cmd.resp[0] & R5_OUT_OF_RANGE) + err = -ERANGE; + else + err = 0; - return 0; + mmc_post_req(card->host, &mrq, err); + + if (nents > 1) + sg_free_table(&sgtable); + + return err; } int sdio_reset(struct mmc_host *host)