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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 97636C433E7 for ; Tue, 1 Sep 2020 17:39:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 773CC2071B for ; Tue, 1 Sep 2020 17:39:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729149AbgIARiw (ORCPT ); Tue, 1 Sep 2020 13:38:52 -0400 Received: from elvis.franken.de ([193.175.24.41]:46057 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729009AbgIARiu (ORCPT ); Tue, 1 Sep 2020 13:38:50 -0400 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1kDAF0-0004vS-00; Tue, 01 Sep 2020 19:38:42 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 46A35C0E70; Tue, 1 Sep 2020 19:38:10 +0200 (CEST) Date: Tue, 1 Sep 2020 19:38:10 +0200 From: Thomas Bogendoerfer To: Christoph Hellwig Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Marek Szyprowski , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, Kyungmin Park , Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-mips@vger.kernel.org, iommu@lists.linux-foundation.org Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Message-ID: <20200901173810.GA25282@alpha.franken.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200901171627.GA8255@lst.de> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Tue, Sep 01, 2020 at 07:16:27PM +0200, Christoph Hellwig wrote: > Well, if IP22 doesn't speculate (which I'm pretty sure is the case), > dma_sync_single_for_cpu should indeeed be a no-op. But then there > also shouldn't be anything in the cache, as the previous > dma_sync_single_for_device should have invalidated it. So it seems like > we are missing one (or more) ownership transfers to the device. I'll > try to look at the the ownership management in a little more detail > tomorrow. this is the problem: /* Always check for received packets. */ sgiseeq_rx(dev, sp, hregs, sregs); so the driver will look at the rx descriptor on every interrupt, so we cache the rx descriptor on the first interrupt and if there was $no rx packet, we will only see it, if cache line gets flushed for some other reason. kick_tx() does a busy loop checking tx descriptors, with just sync_desc_cpu... Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ] 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=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 8A60DC433E6 for ; Tue, 1 Sep 2020 17:38:53 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5B81D2071B for ; Tue, 1 Sep 2020 17:38:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="VGYd5MzT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B81D2071B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=xUvzawVqS6iLuVoKxljZLDgLhW0vHlojCiarqbdra0M=; b=VGYd5MzT8l/DFo8mZP4+LV2t7 9mvmwjPcxxvPri3Vv1zOmjw0TVk1w5Ojola4wX5OW5raHcUCfvPacaQRwFhuDjKRiUesTKn/vdM4F A4YKSmE8BQ8ICIGrqH+3yBAmQ9c99pbjHsVBq0DZZF5N+BkdDKdVKbHESfAjiC1QEX9B+D35Sw9QQ Ixth7Z6l4nNmpVqjOkDmkxaUDUiiWymyul9rCMuGDqPYsVfsxJpeGJhRodyOTMP+JP6QMvPByEr3f 7pqmSRCblMiFApVS35wCJVsb7drQ/RGLxDg2TIF+zqv289RAxCCNh/kZIwSAjRQ47VWY1oCn8qaLm yxBoTMP8w==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDAF6-00007q-Rv; Tue, 01 Sep 2020 17:38:48 +0000 Received: from elvis.franken.de ([193.175.24.41]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDAF4-00007F-U1; Tue, 01 Sep 2020 17:38:47 +0000 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1kDAF0-0004vS-00; Tue, 01 Sep 2020 19:38:42 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 46A35C0E70; Tue, 1 Sep 2020 19:38:10 +0200 (CEST) Date: Tue, 1 Sep 2020 19:38:10 +0200 From: Thomas Bogendoerfer To: Christoph Hellwig Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Message-ID: <20200901173810.GA25282@alpha.franken.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200901171627.GA8255@lst.de> User-Agent: Mutt/1.5.23 (2014-03-12) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200901_133847_166876_4B16F751 X-CRM114-Status: GOOD ( 15.87 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Marek Szyprowski , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, iommu@lists.linux-foundation.org, Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-kernel@vger.kernel.org, Kyungmin Park Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Tue, Sep 01, 2020 at 07:16:27PM +0200, Christoph Hellwig wrote: > Well, if IP22 doesn't speculate (which I'm pretty sure is the case), > dma_sync_single_for_cpu should indeeed be a no-op. But then there > also shouldn't be anything in the cache, as the previous > dma_sync_single_for_device should have invalidated it. So it seems like > we are missing one (or more) ownership transfers to the device. I'll > try to look at the the ownership management in a little more detail > tomorrow. this is the problem: /* Always check for received packets. */ sgiseeq_rx(dev, sp, hregs, sregs); so the driver will look at the rx descriptor on every interrupt, so we cache the rx descriptor on the first interrupt and if there was $no rx packet, we will only see it, if cache line gets flushed for some other reason. kick_tx() does a busy loop checking tx descriptors, with just sync_desc_cpu... Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ] _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme 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=-5.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 4E0C9C433E2 for ; Tue, 1 Sep 2020 17:39:49 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C34972071B for ; Tue, 1 Sep 2020 17:39:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="t4Ef4Ve+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C34972071B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 5640517A9; Tue, 1 Sep 2020 19:38:57 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 5640517A9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1598981987; bh=TEUEbM4vYkBXFl3cUjFLyyUZlmdbqw/yLXBsVNcG3WY=; h=Date:From:To:Subject:References:In-Reply-To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=t4Ef4Ve+k1d1jSN5WiU9jYiXFkK+B8vD+cg0yOhD5g6dHzooY9eIloII5FZvCoGwi tG/juR9/6s8+3q7HV+L+iPSm3nKR47cH/6ZVXU/Yahb44cJhmb+L8BoESXGi6dp6vm 5T8mZJlAozKnqyHcMl/nbrhgb+zPp1wLiH0NMoAo= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id DBD6AF8020D; Tue, 1 Sep 2020 19:38:56 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 01D4AF80217; Tue, 1 Sep 2020 19:38:54 +0200 (CEST) Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by alsa1.perex.cz (Postfix) with ESMTP id 86457F800BA for ; Tue, 1 Sep 2020 19:38:48 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 86457F800BA Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1kDAF0-0004vS-00; Tue, 01 Sep 2020 19:38:42 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 46A35C0E70; Tue, 1 Sep 2020 19:38:10 +0200 (CEST) Date: Tue, 1 Sep 2020 19:38:10 +0200 From: Thomas Bogendoerfer To: Christoph Hellwig Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Message-ID: <20200901173810.GA25282@alpha.franken.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200901171627.GA8255@lst.de> User-Agent: Mutt/1.5.23 (2014-03-12) Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Marek Szyprowski , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, iommu@lists.linux-foundation.org, Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-kernel@vger.kernel.org, Kyungmin Park X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Tue, Sep 01, 2020 at 07:16:27PM +0200, Christoph Hellwig wrote: > Well, if IP22 doesn't speculate (which I'm pretty sure is the case), > dma_sync_single_for_cpu should indeeed be a no-op. But then there > also shouldn't be anything in the cache, as the previous > dma_sync_single_for_device should have invalidated it. So it seems like > we are missing one (or more) ownership transfers to the device. I'll > try to look at the the ownership management in a little more detail > tomorrow. this is the problem: /* Always check for received packets. */ sgiseeq_rx(dev, sp, hregs, sregs); so the driver will look at the rx descriptor on every interrupt, so we cache the rx descriptor on the first interrupt and if there was $no rx packet, we will only see it, if cache line gets flushed for some other reason. kick_tx() does a busy loop checking tx descriptors, with just sync_desc_cpu... Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ] From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Bogendoerfer Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Date: Tue, 1 Sep 2020 19:38:10 +0200 Message-ID: <20200901173810.GA25282@alpha.franken.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20200901171627.GA8255-jcswGhMUV9g@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Sender: "iommu" To: Christoph Hellwig Cc: alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org, linux-ia64-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-mips-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "James E.J. Bottomley" , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Joonyoung Shim , linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Ben Skeggs , Matt Porter , linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-parisc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Seung-Woo Kim , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Kyungmin Park List-Id: nouveau.vger.kernel.org On Tue, Sep 01, 2020 at 07:16:27PM +0200, Christoph Hellwig wrote: > Well, if IP22 doesn't speculate (which I'm pretty sure is the case), > dma_sync_single_for_cpu should indeeed be a no-op. But then there > also shouldn't be anything in the cache, as the previous > dma_sync_single_for_device should have invalidated it. So it seems like > we are missing one (or more) ownership transfers to the device. I'll > try to look at the the ownership management in a little more detail > tomorrow. this is the problem: /* Always check for received packets. */ sgiseeq_rx(dev, sp, hregs, sregs); so the driver will look at the rx descriptor on every interrupt, so we cache the rx descriptor on the first interrupt and if there was $no rx packet, we will only see it, if cache line gets flushed for some other reason. kick_tx() does a busy loop checking tx descriptors, with just sync_desc_cpu... Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ] 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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 C17D2C433E2 for ; Tue, 1 Sep 2020 17:38:50 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9826D2071B for ; Tue, 1 Sep 2020 17:38:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9826D2071B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 6B955870C6; Tue, 1 Sep 2020 17:38:50 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JMAQu4T6TRKE; Tue, 1 Sep 2020 17:38:49 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id CA25D85ECB; Tue, 1 Sep 2020 17:38:49 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id B72C1C07FF; Tue, 1 Sep 2020 17:38:49 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 21C5CC0051 for ; Tue, 1 Sep 2020 17:38:48 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 0E8F986987 for ; Tue, 1 Sep 2020 17:38:48 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bHMdIHK9Btyq for ; Tue, 1 Sep 2020 17:38:47 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by whitealder.osuosl.org (Postfix) with ESMTP id DC8FA86981 for ; Tue, 1 Sep 2020 17:38:46 +0000 (UTC) Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1kDAF0-0004vS-00; Tue, 01 Sep 2020 19:38:42 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 46A35C0E70; Tue, 1 Sep 2020 19:38:10 +0200 (CEST) Date: Tue, 1 Sep 2020 19:38:10 +0200 From: Thomas Bogendoerfer To: Christoph Hellwig Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Message-ID: <20200901173810.GA25282@alpha.franken.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200901171627.GA8255@lst.de> User-Agent: Mutt/1.5.23 (2014-03-12) Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, iommu@lists.linux-foundation.org, Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-kernel@vger.kernel.org, Kyungmin Park X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Tue, Sep 01, 2020 at 07:16:27PM +0200, Christoph Hellwig wrote: > Well, if IP22 doesn't speculate (which I'm pretty sure is the case), > dma_sync_single_for_cpu should indeeed be a no-op. But then there > also shouldn't be anything in the cache, as the previous > dma_sync_single_for_device should have invalidated it. So it seems like > we are missing one (or more) ownership transfers to the device. I'll > try to look at the the ownership management in a little more detail > tomorrow. this is the problem: /* Always check for received packets. */ sgiseeq_rx(dev, sp, hregs, sregs); so the driver will look at the rx descriptor on every interrupt, so we cache the rx descriptor on the first interrupt and if there was $no rx packet, we will only see it, if cache line gets flushed for some other reason. kick_tx() does a busy loop checking tx descriptors, with just sync_desc_cpu... Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ] _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu 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=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 1BD26C433E7 for ; Tue, 1 Sep 2020 17:40:04 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DCE732071B for ; Tue, 1 Sep 2020 17:40:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="IVCpRXoG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DCE732071B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=X1EJBprWLL/65bqs0hecJlBnqkb0H9fIu7qWG3oGASA=; b=IVCpRXoG5tXJLyomrBpttPS4q YHNNPs2zJCLORjs6j5sq9WxPd//5rw3r0PlxOIGs+/j62QQvA3Z3aGjFM/V46yQxmiVnhx/91AKGU H6zaOMWeT4SoXcOGMgvqHUVlEQn7nbXsfkDgGxiWLnKRhYFwE8iefRbRu0/cunQOmp3spMueNvP4O 0pkvpB2AnpfGiWoK7eYD3pM8Rn8hqNVNGy1AsCAtv3gzebfSzjyXqypA2gT3BsixnMcwHGo1DrHsI NRF84Mw83XOUYU8p/BFo9FooWE9l0qDwE4Fo9pRmVA6KK5qRFzYvHx20nbyn1pQbywkwF6hQ0Zkbe 5fsexNNdA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDAF8-00008P-FM; Tue, 01 Sep 2020 17:38:50 +0000 Received: from elvis.franken.de ([193.175.24.41]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDAF4-00007F-U1; Tue, 01 Sep 2020 17:38:47 +0000 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1kDAF0-0004vS-00; Tue, 01 Sep 2020 19:38:42 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 46A35C0E70; Tue, 1 Sep 2020 19:38:10 +0200 (CEST) Date: Tue, 1 Sep 2020 19:38:10 +0200 From: Thomas Bogendoerfer To: Christoph Hellwig Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Message-ID: <20200901173810.GA25282@alpha.franken.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200901171627.GA8255@lst.de> User-Agent: Mutt/1.5.23 (2014-03-12) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200901_133847_166876_4B16F751 X-CRM114-Status: GOOD ( 15.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Marek Szyprowski , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, iommu@lists.linux-foundation.org, Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-kernel@vger.kernel.org, Kyungmin Park Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Sep 01, 2020 at 07:16:27PM +0200, Christoph Hellwig wrote: > Well, if IP22 doesn't speculate (which I'm pretty sure is the case), > dma_sync_single_for_cpu should indeeed be a no-op. But then there > also shouldn't be anything in the cache, as the previous > dma_sync_single_for_device should have invalidated it. So it seems like > we are missing one (or more) ownership transfers to the device. I'll > try to look at the the ownership management in a little more detail > tomorrow. this is the problem: /* Always check for received packets. */ sgiseeq_rx(dev, sp, hregs, sregs); so the driver will look at the rx descriptor on every interrupt, so we cache the rx descriptor on the first interrupt and if there was $no rx packet, we will only see it, if cache line gets flushed for some other reason. kick_tx() does a busy loop checking tx descriptors, with just sync_desc_cpu... Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ] _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Bogendoerfer Date: Tue, 01 Sep 2020 17:38:10 +0000 Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Message-Id: <20200901173810.GA25282@alpha.franken.de> List-Id: References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> In-Reply-To: <20200901171627.GA8255@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Hellwig Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Marek Szyprowski , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, Kyungmin Park , Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-mips@vger.kernel.org, iommu@lists.linux-foundation.org On Tue, Sep 01, 2020 at 07:16:27PM +0200, Christoph Hellwig wrote: > Well, if IP22 doesn't speculate (which I'm pretty sure is the case), > dma_sync_single_for_cpu should indeeed be a no-op. But then there > also shouldn't be anything in the cache, as the previous > dma_sync_single_for_device should have invalidated it. So it seems like > we are missing one (or more) ownership transfers to the device. I'll > try to look at the the ownership management in a little more detail > tomorrow. this is the problem: /* Always check for received packets. */ sgiseeq_rx(dev, sp, hregs, sregs); so the driver will look at the rx descriptor on every interrupt, so we cache the rx descriptor on the first interrupt and if there was $no rx packet, we will only see it, if cache line gets flushed for some other reason. kick_tx() does a busy loop checking tx descriptors, with just sync_desc_cpu... Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]