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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 A9D39C98302 for ; Wed, 23 Sep 2026 04:56:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=KsCIkli++gFDBegtwdL1LQ8y/V8RXq5VkCQBlMaxTeI=; b=RgVvdfzCOPpmmoP9l/yeIw/wex KcONBKbatBGjMqvWbMu6TET344rUbTne5JHsQbWWibMbguB/E5dg9MDoaYjS7i8cp5kUmQ8Ocy0DX zZrGJZ+L3JwQIqr92jVxUtkwtb4Xro2UZ6kpbth6u2z1stunnH6pypp8Cki88jl4QHU82tb3OWvG7 m77/V89qNbmS0YpnzPdTQIlroP+iOX/sDLapFPFRxcKMyZC4IVyGTlaOx44lB1O/rj6DqLnDENX24 z3APtg8weRI7VP3iEoEMaveAgGr5JfojspH6HTxAXwqLQGARM2yag0iZLELLalTUCRciB9xNwE1Hj fyLerCYA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9F1v-000000078SR-0akT; Wed, 23 Sep 2026 04:56:27 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9ExW-000000078Iq-11cl for linux-nvme@bombadil.infradead.org; Wed, 23 Sep 2026 04:51:54 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=KsCIkli++gFDBegtwdL1LQ8y/V8RXq5VkCQBlMaxTeI=; b=MdnZSGtuftX8Cs7E15SiPje+Ng B490QYkHEI2S1kc4q3kleMtRqmcF21Yiq2rAh1zTfS5WCvtiCh8c/siUmjC+2AYoX5feewcZRw+VM s6EPV2hwE2TKJjPyIxx4cWy3S5oLFwG/EsRwUKTJ6BrUSvP4l32qM7/yrrabj3507uNsBIzgQezeI pa/DATOuhuJ+E/FIq/KTqYvmwG5VF5yPeyJqeqSbKkqf0+aEJyue6xQLUatEhVIl0dTfY7DkRuKPe m+sj+MSO9J/tPFnvkE+L1CtLviULJIhjIiMgG7RMc/1REV7Dwl2mmCt8o/1XEiGQnfEoL9yy7pVXG wFwnqIuA==; Received: from verein.lst.de ([213.95.11.211]) by desiato.infradead.org with esmtps (Exim 4.99.2 #2 (Red Hat Linux)) id 1x9ExR-0000000ELkS-3Cou for linux-nvme@lists.infradead.org; Wed, 23 Sep 2026 04:51:52 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 2B01F68BFE; Wed, 23 Sep 2026 06:51:44 +0200 (CEST) Date: Wed, 23 Sep 2026 06:51:43 +0200 From: Christoph Hellwig To: Pavel Begunkov Cc: Christoph Hellwig , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, Sumit Semwal , Christian =?iso-8859-1?Q?K=F6nig?= , Keith Busch , Sagi Grimberg , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Jens Axboe , Nitesh Shetty , Kanchan Joshi , Anuj Gupta , Tushar Gohad , William Power , Phil Cayton , Matthew Brost , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Benjamin Marzinski , dm-devel@lists.linux.dev Subject: Re: [PATCH v6 04/13] block: introduce dma map backed bio type Message-ID: <20260923045143.GA26231@lst.de> References: <20260922131610.GA30468@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260923_055150_835184_E054D412 X-CRM114-Status: GOOD ( 16.69 ) X-Mailman-Approved-At: Tue, 22 Sep 2026 21:56:25 -0700 X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Tue, Sep 22, 2026 at 02:54:25PM +0100, Pavel Begunkov wrote: >> >> Can you please expland on the splitting considerations a bit? Preferably >> both in a comment for the details, and in the commit log for how we >> arrived at them and why they are fine for now? > > I'll add something to the commit log, but not sure which specific > details in comments you mean. Do you want me to expand the comment > above limiting the number of segments? Maybe I should add there that > it's stricter than necessary and might cause more splitting than > necessary? This one: Yes, explain why we apply a relatively arbitrary limit not fully exploiting the hardware capabilities, and why we thing that is okay.