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 9DDF1C433EF for ; Wed, 29 Jun 2022 06:46:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232204AbiF2Gqe (ORCPT ); Wed, 29 Jun 2022 02:46:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231629AbiF2Gqd (ORCPT ); Wed, 29 Jun 2022 02:46:33 -0400 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A84042ED6C; Tue, 28 Jun 2022 23:46:32 -0700 (PDT) Received: by verein.lst.de (Postfix, from userid 2407) id DA93F67373; Wed, 29 Jun 2022 08:46:29 +0200 (CEST) Date: Wed, 29 Jun 2022 08:46:29 +0200 From: Christoph Hellwig To: Logan Gunthorpe 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 , Christoph Hellwig , Dan Williams , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , 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 Subject: Re: [PATCH v7 16/21] block: add check when merging zone device pages Message-ID: <20220629064629.GC17576@lst.de> References: <20220615161233.17527-1-logang@deltatee.com> <20220615161233.17527-17-logang@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220615161233.17527-17-logang@deltatee.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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. 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 smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 09B54C43334 for ; Wed, 29 Jun 2022 06:46:37 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id A3A1C60C2B; Wed, 29 Jun 2022 06:46:36 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org A3A1C60C2B X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id YW_hhywC6Apc; Wed, 29 Jun 2022 06:46:36 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp3.osuosl.org (Postfix) with ESMTPS id 919BB60C13; Wed, 29 Jun 2022 06:46:35 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org 919BB60C13 Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 671E1C0032; Wed, 29 Jun 2022 06:46:35 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [IPv6:2605:bc80:3010::136]) by lists.linuxfoundation.org (Postfix) with ESMTP id D0680C002D for ; Wed, 29 Jun 2022 06:46:33 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id AA94C60C13 for ; Wed, 29 Jun 2022 06:46:33 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org AA94C60C13 X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 0H-IvxnWgEUi for ; Wed, 29 Jun 2022 06:46:33 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org 06F0360B5E Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by smtp3.osuosl.org (Postfix) with ESMTPS id 06F0360B5E for ; Wed, 29 Jun 2022 06:46:32 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id DA93F67373; Wed, 29 Jun 2022 08:46:29 +0200 (CEST) Date: Wed, 29 Jun 2022 08:46:29 +0200 From: Christoph Hellwig To: Logan Gunthorpe Subject: Re: [PATCH v7 16/21] block: add check when merging zone device pages Message-ID: <20220629064629.GC17576@lst.de> References: <20220615161233.17527-1-logang@deltatee.com> <20220615161233.17527-17-logang@deltatee.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220615161233.17527-17-logang@deltatee.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: linux-pci@vger.kernel.org, Dave Hansen , linux-nvme@lists.infradead.org, Stephen Bates , linux-mm@kvack.org, Jason Ekstrand , Ira Weiny , Christoph Hellwig , 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 , Christian =?iso-8859-1?Q?K=F6nig?= 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 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. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu