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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F4170CCA47C for ; Wed, 29 Jun 2022 16:06:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234042AbiF2QGO (ORCPT ); Wed, 29 Jun 2022 12:06:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233829AbiF2QGM (ORCPT ); Wed, 29 Jun 2022 12:06:12 -0400 Received: from ale.deltatee.com (ale.deltatee.com [204.191.154.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08F926396; Wed, 29 Jun 2022 09:06:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:In-Reply-To:From:References:Cc:To: MIME-Version:Date:Message-ID:content-disposition; bh=7Il3Zmz7S/H0NpQetmZjc06R/zh7uKcDBAajLC9gk7k=; b=nQI+rf6typETAhwsXDC03rqH1s V164Y6PeH/wetb3LsK1Agsg11/TBxGJrqtz9PS3ZCkdd8xr4Tq3i6g50Fh8k7KpOVCJf71tRgxbIH njTbD+6wn0OaEcJplIK7kNG6yhTWpzvNbrG4L/3iG+OAOYrLdNmjf+5QpEyqcx7jaj/nE8Z8TguZc jVHgBb1v3Ga3S+jBuSfll3H9aSztuVx1Un8QlkO5yuAX5Saz9FlonIBzN4iJ0dd8BEbHTqvsVvRi1 T3g4LOg96bAhr2/nF2mMRWewmYCIhMV+dOlF5CozLQiN2Y1LRjq0qQmuCMGhP54hZ4GTTGSsVNp3Y Ww9rCnag==; Received: from s0106a84e3fe8c3f3.cg.shawcable.net ([24.64.144.200] helo=[192.168.0.10]) by ale.deltatee.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1o6aCX-002SQa-6C; Wed, 29 Jun 2022 10:06:02 -0600 Message-ID: <7da06e08-7dd1-f37c-4382-bc59a1b1e819@deltatee.com> Date: Wed, 29 Jun 2022 10:06:00 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Content-Language: en-CA To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Dan Williams , Jason Gunthorpe , =?UTF-8?Q?Christian_K=c3=b6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni , Ralph Campbell References: <20220615161233.17527-1-logang@deltatee.com> <20220615161233.17527-17-logang@deltatee.com> <20220629064629.GC17576@lst.de> From: Logan Gunthorpe In-Reply-To: <20220629064629.GC17576@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 24.64.144.200 X-SA-Exim-Rcpt-To: hch@lst.de, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, sbates@raithlin.com, dan.j.williams@intel.com, jgg@ziepe.ca, christian.koenig@amd.com, jhubbard@nvidia.com, ddutile@redhat.com, willy@infradead.org, daniel.vetter@ffwll.ch, dave.b.minturn@intel.com, jason@jlekstrand.net, dave.hansen@linux.intel.com, jianxin.xiong@intel.com, helgaas@kernel.org, ira.weiny@intel.com, robin.murphy@arm.com, martin.oliveira@eideticom.com, ckulkarnilinux@gmail.com, rcampbell@nvidia.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v7 16/21] block: add check when merging zone device pages X-SA-Exim-Version: 4.2.1 (built Sat, 13 Feb 2021 17:57:42 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2022-06-29 00:46, Christoph Hellwig wrote: > On Wed, Jun 15, 2022 at 10:12:28AM -0600, Logan Gunthorpe wrote: >> Consecutive zone device pages should not be merged into the same sgl >> or bvec segment with other types of pages or if they belong to different >> pgmaps. Otherwise getting the pgmap of a given segment is not possible >> without scanning the entire segment. This helper returns true either if >> both pages are not zone device pages or both pages are zone device >> pages with the same pgmap. >> >> Add a helper to determine if zone device pages are mergeable and use >> this helper in page_is_mergeable(). > > Any reason not to simply set REQ_NOMERGE for these requests? We > can't merge for passthrough requests anyway, and genrally don't merge > for direct I/O either, so adding all this overhead seems a bit pointless. Hmm, I suppose we could also ensure that REQ_NOMERGE is set in a bio before setting FOLL_PCI_P2PDMA in bio_map_user_iov() and __bio_iov_iter_get_pages(). Assuming it's always set for any direct I/O. I'll look into it. Logan 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 Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4291DC433EF for ; Wed, 29 Jun 2022 16:06:13 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id B605B83FAB; Wed, 29 Jun 2022 16:06:12 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org B605B83FAB Authentication-Results: smtp1.osuosl.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.a=rsa-sha256 header.s=20200525 header.b=nQI+rf6t X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id qbfnXVUL9vjA; 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Wed, 29 Jun 2022 10:06:02 -0600 Message-ID: <7da06e08-7dd1-f37c-4382-bc59a1b1e819@deltatee.com> Date: Wed, 29 Jun 2022 10:06:00 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Content-Language: en-CA To: Christoph Hellwig References: <20220615161233.17527-1-logang@deltatee.com> <20220615161233.17527-17-logang@deltatee.com> <20220629064629.GC17576@lst.de> From: Logan Gunthorpe In-Reply-To: <20220629064629.GC17576@lst.de> X-SA-Exim-Connect-IP: 24.64.144.200 X-SA-Exim-Rcpt-To: hch@lst.de, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, sbates@raithlin.com, dan.j.williams@intel.com, jgg@ziepe.ca, christian.koenig@amd.com, jhubbard@nvidia.com, ddutile@redhat.com, willy@infradead.org, daniel.vetter@ffwll.ch, dave.b.minturn@intel.com, jason@jlekstrand.net, dave.hansen@linux.intel.com, jianxin.xiong@intel.com, helgaas@kernel.org, ira.weiny@intel.com, robin.murphy@arm.com, martin.oliveira@eideticom.com, ckulkarnilinux@gmail.com, rcampbell@nvidia.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v7 16/21] block: add check when merging zone device pages X-SA-Exim-Version: 4.2.1 (built Sat, 13 Feb 2021 17:57:42 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Cc: linux-pci@vger.kernel.org, Dave Hansen , linux-nvme@lists.infradead.org, Stephen Bates , linux-mm@kvack.org, Jason Ekstrand , Ira Weiny , Minturn Dave B , Martin Oliveira , Matthew Wilcox , Jason Gunthorpe , Chaitanya Kulkarni , Bjorn Helgaas , Daniel Vetter , Ralph Campbell , John Hubbard , linux-block@vger.kernel.org, Dan Williams , Xiong Jianxin , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Robin Murphy , =?UTF-8?Q?Christian_K=c3=b6nig?= 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 2022-06-29 00:46, Christoph Hellwig wrote: > On Wed, Jun 15, 2022 at 10:12:28AM -0600, Logan Gunthorpe wrote: >> Consecutive zone device pages should not be merged into the same sgl >> or bvec segment with other types of pages or if they belong to different >> pgmaps. Otherwise getting the pgmap of a given segment is not possible >> without scanning the entire segment. This helper returns true either if >> both pages are not zone device pages or both pages are zone device >> pages with the same pgmap. >> >> Add a helper to determine if zone device pages are mergeable and use >> this helper in page_is_mergeable(). > > Any reason not to simply set REQ_NOMERGE for these requests? We > can't merge for passthrough requests anyway, and genrally don't merge > for direct I/O either, so adding all this overhead seems a bit pointless. Hmm, I suppose we could also ensure that REQ_NOMERGE is set in a bio before setting FOLL_PCI_P2PDMA in bio_map_user_iov() and __bio_iov_iter_get_pages(). Assuming it's always set for any direct I/O. I'll look into it. Logan _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu