From: Christoph Hellwig <hch@lst.de>
To: Chuck Lever <cel@kernel.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
Leon Romanovsky <leon@kernel.org>, Christoph Hellwig <hch@lst.de>,
linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org,
NeilBrown <neilb@ownmail.net>, Jeff Layton <jlayton@kernel.org>,
Olga Kornievskaia <okorniev@redhat.com>,
Dai Ngo <dai.ngo@oracle.com>, Tom Talpey <tom@talpey.com>,
Chuck Lever <chuck.lever@oracle.com>
Subject: Re: [PATCH v1 4/4] svcrdma: use bvec-based RDMA read/write API
Date: Thu, 15 Jan 2026 17:29:29 +0100 [thread overview]
Message-ID: <20260115162929.GC17257@lst.de> (raw)
In-Reply-To: <20260114143948.3946615-5-cel@kernel.org>
On Wed, Jan 14, 2026 at 09:39:48AM -0500, Chuck Lever wrote:
> The structure size reduction is significant: the previous inline
> scatterlist array of RPCSVC_MAXPAGES entries (4KB or more) is
> replaced with a pointer to a dynamically allocated bvec array,
> bringing the fixed structure size down to approximately 100 bytes.
Can you explain why this switches to the dynamic allocation?
To me that seems like a separate trade-off to bvec vs scatterlist.
> * Each WR chain handles a single contiguous server-side buffer,
> - * because scatterlist entries after the first have to start on
> + * because bio_vec entries after the first have to start on
> * page alignment. xdr_buf iovecs cannot guarantee alignment.
For both the old and new version, can you explain they have to
start on a page boundary? Because that's not how scatterlists or
bvecs work in general. I guess this just documents the sunrpc
limits, but somehow projects it to these structures?
next prev parent reply other threads:[~2026-01-15 16:29 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-14 14:39 [PATCH v1 0/4] Add a bio_vec based API to core/rw.c Chuck Lever
2026-01-14 14:39 ` [PATCH v1 1/4] RDMA/core: add bio_vec based RDMA read/write API Chuck Lever
2026-01-15 15:53 ` Christoph Hellwig
2026-01-16 11:33 ` Leon Romanovsky
2026-01-16 14:52 ` Christoph Hellwig
2026-01-16 14:57 ` Chuck Lever
2026-01-16 21:14 ` Leon Romanovsky
2026-01-16 21:24 ` Leon Romanovsky
2026-01-16 21:49 ` Chuck Lever
2026-01-17 16:20 ` Leon Romanovsky
2026-01-19 6:52 ` Christoph Hellwig
2026-01-19 10:28 ` Leon Romanovsky
2026-01-19 12:03 ` Christoph Hellwig
2026-01-19 14:37 ` Chuck Lever
2026-01-19 18:34 ` Leon Romanovsky
2026-01-14 14:39 ` [PATCH v1 2/4] RDMA/core: use IOVA-based DMA mapping for bvec RDMA operations Chuck Lever
2026-01-15 15:58 ` Christoph Hellwig
2026-01-14 14:39 ` [PATCH v1 3/4] RDMA/core: add MR support for bvec-based " Chuck Lever
2026-01-15 15:58 ` Christoph Hellwig
2026-01-16 11:42 ` Leon Romanovsky
2026-01-16 14:50 ` Christoph Hellwig
2026-01-16 21:16 ` Leon Romanovsky
2026-01-14 14:39 ` [PATCH v1 4/4] svcrdma: use bvec-based RDMA read/write API Chuck Lever
2026-01-15 9:51 ` Leon Romanovsky
2026-01-15 16:29 ` Christoph Hellwig [this message]
2026-01-15 18:29 ` Chuck Lever
2026-01-15 21:53 ` Chuck Lever
2026-01-16 9:38 ` Christoph Hellwig
2026-01-15 9:50 ` [PATCH v1 0/4] Add a bio_vec based API to core/rw.c Leon Romanovsky
2026-01-15 15:46 ` Christoph Hellwig
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