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 E77DEC369AB for ; Fri, 18 Apr 2025 11:19:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E45CE680004; Fri, 18 Apr 2025 07:19:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DA7D7680002; Fri, 18 Apr 2025 07:19:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C1EDA680004; Fri, 18 Apr 2025 07:19:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 9EC31680002 for ; Fri, 18 Apr 2025 07:19:54 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id B13821A1BD6 for ; Fri, 18 Apr 2025 11:19:55 +0000 (UTC) X-FDA: 83346919950.14.94AF46B Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf08.hostedemail.com (Postfix) with ESMTP id 26D75160004 for ; Fri, 18 Apr 2025 11:19:54 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=WdeyXvfa; spf=pass (imf08.hostedemail.com: domain of leon@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=leon@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1744975194; 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:dkim-signature; bh=Apema9hJmPv6bbP4STg4j5++huvkZ85a9+z8ec7sdgk=; b=EZ/UAFGqNjx7cXnbNTBxVMV9EfNi+Vl5UloHgVaW0oV1nInU2VKAOwWJSzBZqnu0cKwCEX ChUaz4DCqGbLSmD82h7gtvvvjKjxP7S+gJpiWkLmsEinX6/OTPQsXbpsBsHYAAJJbzbWT8 qag5TG7QcH6qDU7TCRIv2xJI55NlBcc= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=WdeyXvfa; spf=pass (imf08.hostedemail.com: domain of leon@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=leon@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1744975194; a=rsa-sha256; cv=none; b=ti3b/XwQfm82zdZz3b72tBdNooAg519vfdCqjs4J8HE6T+VSlffS7KHYtroCobnMmH3MPK 9l4IsyXDICausIQyfPLhOua7fLYK03kQhMYYr/JDiPTxCx1bl+i4QzJcdGZTJPvdq32PU6 JqJ7kF9FSZ+W7rmPNFQk2B0v33SFho4= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id CB66B61120; Fri, 18 Apr 2025 11:19:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 98E2DC4CEE2; Fri, 18 Apr 2025 11:19:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744975193; bh=A7wvqwnqYa5lljVCih9QNkNHMM3IhtbdB0k5O3y2uik=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WdeyXvfarIVDZXIlsrZR6q+ZWN3+pN643rg0mOwmYV5A6pKmeRqB/JWY/8ObUAnJi Y1EqzpJAMsZxftxRUhP7InpbxA68zM7a6DddpAF30J+LhDbBYnrB+4R7SOQ7Z46AGH mSi5EInuDvbHAH3PcbwmhGvxSQxVx4wSnWHM7vjrcR9bDC4KkeIuhcfdENyorCWU9U 438m+H5AQfvv/rBCcHLE3C4f92y96s5caeLMC+3sz+c/1NNlmdYlYVYpkbEWVlcolR bcqe1xg8mMIU5XVaCBr+Sxo15YaqwuuASTpzG37swqcijwKEEM/LYAGrbVM4ttt8Qo U7pz/uTfDL03g== Date: Fri, 18 Apr 2025 14:19:49 +0300 From: Leon Romanovsky To: Damien Le Moal Cc: Marek Szyprowski , Jens Axboe , Christoph Hellwig , Keith Busch , Kanchan Joshi , Jake Edge , Jonathan Corbet , Jason Gunthorpe , Zhu Yanjun , Robin Murphy , Joerg Roedel , Will Deacon , Sagi Grimberg , Bjorn Helgaas , Logan Gunthorpe , Yishai Hadas , Shameer Kolothum , Kevin Tian , Alex Williamson , =?iso-8859-1?B?Suly9G1l?= Glisse , Andrew Morton , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, iommu@lists.linux.dev, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, Niklas Schnelle , Chuck Lever , Luis Chamberlain , Matthew Wilcox , Dan Williams , Chaitanya Kulkarni , Nitesh Shetty Subject: Re: [PATCH v8 24/24] nvme-pci: optimize single-segment handling Message-ID: <20250418111949.GC199604@unreal> References: <670389227a033bd5b7c5aa55191aac9943244028.1744825142.git.leon@kernel.org> <1284adf3-7e93-4530-9921-408c5eaeb337@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1284adf3-7e93-4530-9921-408c5eaeb337@kernel.org> X-Stat-Signature: yhdqhiojbhxrhh6twk6cigu367dmornz X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 26D75160004 X-Rspam-User: X-HE-Tag: 1744975193-410184 X-HE-Meta: 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 TN22QxJE JEYo54EjyhRt+lTeBIxaldnlZYzHhqCZPHe84hPfRDTdv3i5Qv6D3UYZggCf4INJNXHy/wfmJh3Az0zhPa55LPpFHTG0S7ZcOV9tC4ZXl+HMYF+qnKT8lqO77SkAl0XvX4j0XButiEOlVIVVIv02HAhMBpH6/lD8tHhyIkPM1IN4FU3whZc3xQOjka3zQ75YJftLvr7r2Fs/A16J7miPJBafDyEX4v4FE7o4LHktfFenNsKZ7QfmL914580h31Ser+VkIjt1bQHBPbkwAMOr8k4jrPS31zClXROsCn2pqfNdSz1w= 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: List-Subscribe: List-Unsubscribe: On Fri, Apr 18, 2025 at 05:02:38PM +0900, Damien Le Moal wrote: > On 4/18/25 15:47, Leon Romanovsky wrote: > > From: Kanchan Joshi > > > > blk_rq_dma_map API is costly for single-segment requests. > > Avoid using it and map the bio_vec directly. > > > > Signed-off-by: Kanchan Joshi > > Signed-off-by: Nitesh Shetty > > Signed-off-by: Leon Romanovsky > > --- > > drivers/nvme/host/pci.c | 65 +++++++++++++++++++++++++++++++++++++---- > > 1 file changed, 60 insertions(+), 5 deletions(-) <...> > > static void nvme_unmap_data(struct nvme_dev *dev, struct request *req) > > { > > struct nvme_iod *iod = blk_mq_rq_to_pdu(req); > > + unsigned int nr_segments = blk_rq_nr_phys_segments(req); > > + dma_addr_t dma_addr; > > + > > + if (nr_segments == 1 && (iod->flags & IOD_SINGLE_SEGMENT)) { > > nvme_pci_setup_prps() calls nvme_try_setup_prp_simple() which sets > IOD_SINGLE_SEGMENT if and only if the req has a single phys segment. So why do > you need to count the segments again here ? Looking at the flag only should be > enough, no ? Yes, you are right. There is no need in extra check of nr_segments and it is enough to rely on IOD_SINGLE_SEGMENT. Thanks