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 8906AECAAA3 for ; Fri, 26 Aug 2022 19:45:15 +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=x+UMVnujX+X39oLXzhe/HhYNdkWkFHYnX0Mj23junlg=; b=vsV8uRYZ1S+vc/Azy5e9R3wF+k LbKD3YZh0mzo7OkupDjMGNnhhYWuhWFv/anGb5DBLpUPAvzfC9TNomO6ckco/N6nz3c00zd67xHL+ de9KXVzxWRLTcM7RkhKQKmqAX+Up2YzXUBoBHVqmmxegGo7wMaWdGklSKI0Wtd/5A0bxvdO6MYpPr JRsC9thJ02PvF6KT2AnBdmu8VLa/ZYTBHwjRJTDc2TdmdbMtKjZoJROlhOMOxs/HONCF2E/Chcr2l /Ul/P9lb9abAUcdHmEqvoEykI0CFx5ZW9MACsbn3oM34GcxbAXxir2Z4gDVCXp4nYo7G6v/9oI6A9 gP2ucXwQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oRfGO-00Ascf-TI; Fri, 26 Aug 2022 19:45:08 +0000 Received: from zeniv.linux.org.uk ([2a03:a000:7:0:5054:ff:fe1c:15ff]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oRf76-00Akca-Nl for linux-nvme@lists.infradead.org; Fri, 26 Aug 2022 19:35:34 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=x+UMVnujX+X39oLXzhe/HhYNdkWkFHYnX0Mj23junlg=; b=WR6NHCgYDvvQiuvmHDFS2QjkrD zxpBieFdz8zXKZaTBOZ2eo3bvI8UEm6kuTHCwfdD82/ES84mG3sFgChiT3EpJztCVAh8wESBXuC7k sbpAKpUlPN9wYol+RqgklQi0pBZO1Mq3IThb0O4IUcQkJteSr4m+63qwc+FYQRdRztleSnIeqcCIK Vz82hYFQ0hRBH7Wsk4MVbxytjoAXW5MNUxLi4GkzKOQAVqKWL5rqmmHBnId0c8nkVR1cCVoUA/n5r Tf/PWye0IFxrahKkq+FEMOyqyGuTHR/Fq+fEew2pZdwy6OaxM0R57lZ1zia4Y1fnczYhD6mPm3NCC Je95WuDg==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.95 #2 (Red Hat Linux)) id 1oRf6r-008dnk-VB; Fri, 26 Aug 2022 19:35:18 +0000 Date: Fri, 26 Aug 2022 20:35:17 +0100 From: Al Viro To: Keith Busch Cc: "Fabio M. De Francesco" , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , James Smart , Ira Weiny , "Venkataramanan, Anirudh" , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Chaitanya Kulkarni Subject: Re: [PATCH v3 1/1] nvmet-tcp: Don't kmap() pages which can't come from HIGHMEM Message-ID: References: <20220822142438.5954-1-fmdefrancesco@gmail.com> <20220822142438.5954-2-fmdefrancesco@gmail.com> <2887364.VdNmn5OnKV@opensuse> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220826_123532_821488_833676BA X-CRM114-Status: GOOD ( 10.13 ) 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 Fri, Aug 26, 2022 at 12:35:09PM -0600, Keith Busch wrote: > > Can you please provide further information or links to documentation? > > This kvec/bvec talk is a digression from your original goal: reduce unnecessary > kmap() usage. If anyone wants to take on the bvec optimization in this code > path, then by all means lets do it in a separate patch. Oh? And why is a switch to iov_iter_bvec() *not* a reduction of kmap() usage? ITER_BVEC methods use kmap_local() for data transfers, TYVM...