From: Christoph Hellwig <hch@infradead.org>
To: Keith Busch <kbusch@meta.com>
Cc: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
hch@lst.de, axboe@kernel.dk, Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCHv3 2/2] nvme: remove virtual boundary for sgl capable devices
Date: Mon, 25 Aug 2025 06:49:23 -0700 [thread overview]
Message-ID: <aKxp49SdTknkO1fb@infradead.org> (raw)
In-Reply-To: <20250821204420.2267923-3-kbusch@meta.com>
On Thu, Aug 21, 2025 at 01:44:20PM -0700, Keith Busch wrote:
> + /*
> + * The virtual boundary mask is not necessary for PCI controllers that
> + * support SGL for DMA. It's only necessary when using PRP. Admin
> + * queues only support PRP, and fabrics drivers currently don't report
> + * what boundaries they require, so set the virtual boundary for
> + * either.
> + */
> + if (!nvme_ctrl_sgl_supported(ctrl) || admin ||
> + ctrl->ops->flags & NVME_F_FABRICS)
> + lim->virt_boundary_mask = NVME_CTRL_PAGE_SIZE - 1;
Fabrics itself never needs the virt boundary. And for TCP which is a
software only transport I think we can just do away with it. For
FC I suspect we can do away with it as well, as all the FC HBA support
proper SGLs. For RDMA the standard MR methods do require the virtual
boundary, but somewhat recent Mellanox / Nvidia hardware does not.
No need for you to update all these, but I think having the transport
advertise the capability is probably better than a bunch of random
conditions in the core code.
prev parent reply other threads:[~2025-08-25 15:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-21 20:44 [PATCHv3 0/2] block+nvme: reducing virtual boundary mask reliance Keith Busch
2025-08-21 20:44 ` [PATCHv3 1/2] block: accumulate segment page gaps per bio Keith Busch
2025-08-25 13:46 ` Christoph Hellwig
2025-08-25 14:10 ` Keith Busch
2025-08-26 13:03 ` Christoph Hellwig
2025-08-26 13:47 ` Keith Busch
2025-08-26 13:57 ` Christoph Hellwig
2025-08-26 22:33 ` Keith Busch
2025-08-27 7:37 ` Christoph Hellwig
2025-08-30 1:47 ` Keith Busch
2025-09-02 5:36 ` Christoph Hellwig
2025-08-21 20:44 ` [PATCHv3 2/2] nvme: remove virtual boundary for sgl capable devices Keith Busch
2025-08-25 13:49 ` Christoph Hellwig [this message]
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