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b=FJq30b87/TflnB9DVVipFNU57Znk7OWclwNiEv1U1CkREJE7TpnQD5/hqoZtIuTZJ dTPGGSPbMLaLEb2zNkLd3Q778H6VAa8OOBofqBahNpMdxezfgyVohmR6Rd9GiEqit6 rqQQDP3Pc8mFmUp7rVwkCwExrNjkUbpZzr5cC8mMpJGiZVgmXx+K5vas3ebglhBMWf RVeOeSh6BNTXES/fWcmFmi51oMgzzUf4ye8EeNe7AB8tBKDLrYmlZv3p0jO5PK+S/3 YSBQMCWgd1JztmQ+CpvrmAO4qjEfa68n3WyOSSCxk7QhEyBqnidI1p8GTad9JjjkB8 RxKZi4poFx/gQ== Date: Tue, 22 Apr 2025 14:36:43 +0300 From: Leon Romanovsky To: Christoph Hellwig Cc: Marek Szyprowski , Jens Axboe , 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: <20250422113643.GE48485@unreal> References: <670389227a033bd5b7c5aa55191aac9943244028.1744825142.git.leon@kernel.org> <20250422043955.GA28077@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250422043955.GA28077@lst.de> X-Rspamd-Queue-Id: DAAE11C0002 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: mrcuzepnmxi5jy9sfn6c8ticwmdb9i6t X-HE-Tag: 1745321810-865446 X-HE-Meta: U2FsdGVkX1/w6n0jx7mxyiEiaHmMSDthHmCoHNbX+RUI1I30WfqmbaHPg9CmC7noNSLgJFK2buL2jfCpoxH0LAMiYqRA/WexNrVB6JkwFxXLVYhQGPhx6Oq7vqUUlNYz7l5WXikDm4Gch2OMTJHQMj0ZCWrLaz0hR8P6f/FjvqMf3GgL0W/Mgd8ijFq5uVA/90x2tawSfI3Cmkqglo0kcbQ/9ZOYqEeuYBqICYHEdZiSZW+IUDW7nUnn7BdwgLoqlkcPyX067503AF0I81BQEzn+hsyzWr0mRz7mZPxeJmMzku2h8QuiPRnKUDBg6N+mJhhgK+/0fDD6Zfr4VluE6Tt+gpKXtW3UqPC/w/uKrFnSTB7klfBK6OuPxUCd6Xs3WuhE+syxo3krcPlmKndYO6EaQrCmjjFqv3pj7/geK39agIljx8d8dN0VHNHlm1weMEjrIjrLzbbk6ReYbu0jR5yMdHYOUx2xKpX0FNe6OT+SBY49BSFMCqgBGQCH8sEz2+KZZ9sK0Y7AkXzT2hID60ZB8mc/lFhkFbMM8YmU/doPOdILzzCsLX1S2BYwTvGIwXp2MLamURue9gijTVgCgjqBdzeJG+rfZ9cuP1km5DV4wCa/8dYhm5EwM4nWFLSA/i8uaoyJhNb9n1gt46jylpiRRrTmmiUA2ZcbUHofQAAs7tBvddADslLrPI3CxdGXta2Q4cWSZYB1iwGo7wGQYRKFsqLf+5TFmzT7iG499tNqwjF5fiD7zv+6ONl8kiJQpcNFvBLaIn4c2IkunYE34HtFIFQ6EZRxln5gbv6HnlyzEKUyTmdWLFWsDXyBwsjgT43DH9/uVbQom/ZtT/xc/vNLzJZVae50frBzQ7nZ+5PT3+sE0v6HCvMp3k8HCfqJCWFjgbUbG6Nj6iVwR8XXCUfr1VV9bqoZfJ5TrkeyUz0+7vrDzzhSfrxGAmcISVGW50DPu2uJBlwSvJqiUJG QT9JqVhd 25QD773Emdhk7Kqcn2ILQcSPJfCkaHI2f0zI8KZrj5324IrzF8bSQdSvRczJyto98WntJeOUOMt2fV1XbUvLTUBXFbC5DtEmPUQJroim/3qk1+cQxl5Wba2AW7g4Ppdh6gsTRIzBKF/Cz1clr//jJ0SvqeKKjsByq8Dr6a5+yjZgvOsM0PhuXJIdFqf6q9nqjVR4/kB7nLVcfJYpDCRwq8CwEK5+iWtoDBwGD7WxNkBNJfKRek+8A7zmSRQdfS9rUjLcDGABq3uLQ/v4aliBMWpirUg== 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 Tue, Apr 22, 2025 at 06:39:56AM +0200, Christoph Hellwig wrote: > On Fri, Apr 18, 2025 at 09:47:54AM +0300, 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. > > This needs to be folded into the earlier patches or split prep patches > instead of undoing work done earlier, preferably combined with a bit > of code movement so that the new nvme_try_setup_prp_simple stays in > the same place as before and the diff shows it reusing code. > > E.g. change > > "nvme-pci: use a better encoding for small prp pool allocations" to > already use the flags instead of my boolean, and maybe include > abort in the flags instead of using a separate bool so that we > don't increase hte iod size. > > Slot in a new patch after that that dropping the single SGL segment > fastpath if we think we don't need that, although if we need the PRP > one I suspect that one would still be very helpful as well. > > Add a patch if we want the try_ version of, although when keeping > the optimization for SGLs as well that are will look a bit different. I uploaded new tag dma-split-Apr-22 with the changes. At the end, I decided to keep SGL optimized path too, but didn't create separate patch for try_* variants as they require block iterator, which is introduced in conversion patch only. > > I'm happy to give away my patch authorship credits if that helps with > the folding. I kept you as an author. Please advise if I need to change it to be someone else. Thanks