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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D19F9C433EF for ; Wed, 29 Jun 2022 06:46:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 698C28E0005; Wed, 29 Jun 2022 02:46:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 621628E0002; Wed, 29 Jun 2022 02:46:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4C2858E0005; Wed, 29 Jun 2022 02:46:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 370768E0002 for ; Wed, 29 Jun 2022 02:46:33 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 0B41321488 for ; Wed, 29 Jun 2022 06:46:33 +0000 (UTC) X-FDA: 79630339866.14.5FE1F68 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf23.hostedemail.com (Postfix) with ESMTP id 8F90F140024 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 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) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656485192; a=rsa-sha256; cv=none; b=Kd8Ivw/sSHOXUAPWGQirA2fzyD70kaGQaUsQ5iT9OxAOVjFPcGbubRMP+Ccyd/N4B3wu0M ZpRX2f8yvgUBa15OAn6RrmythZpH3NgG7XWvLAaSJy7jBOumi9R80AKNcR4GTlVBG3zQxl hOWPvC369MWlnzNiAb7vOCi1vdChUwk= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=none; dmarc=none; spf=none (imf23.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656485192; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JrjO8tBU/JzWiQQVO/ztz9PRUNAKEwkNcVzGxTEVVNE=; b=lKqZGq9AUL/4eqJwGnwy5I2Zix4Unwx75MVDm7hU824lXoP4Gxa5SnZz2326qOoVHkLULW ZW1SJUjBgcOdlt+4iyw06+bBGMEbh/Z/g1UQxrEY0QI6vUrzLtHzlcsq1iDlB/7C9dduLk SWuEaDUAb4//D1DmgYngR/pi6j3D5Ik= X-Stat-Signature: w7ig19djn4pzb5k6zu5g1wrtx4pczpuf X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8F90F140024 Authentication-Results: imf23.hostedemail.com; dkim=none; dmarc=none; spf=none (imf23.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de X-HE-Tag: 1656485192-143889 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.