From: Christoph Hellwig <hch@lst.de>
To: Chuck Lever <cel@kernel.org>
Cc: Leon Romanovsky <leon@kernel.org>, Christoph Hellwig <hch@lst.de>,
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>,
linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org,
Chuck Lever <chuck.lever@oracle.com>,
Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH v3 4/4] svcrdma: Use contiguous pages for RDMA Read sink buffers
Date: Tue, 17 Mar 2026 15:28:55 +0100 [thread overview]
Message-ID: <20260317142855.GD4367@lst.de> (raw)
In-Reply-To: <20260313194201.5818-5-cel@kernel.org>
On Fri, Mar 13, 2026 at 03:42:01PM -0400, Chuck Lever wrote:
> Suggested-by: Christoph Hellwig <hch@infradead.org>
I think that's a bit too much credit. I just wondered why sunrpc can't
coalesce pages itself.
> +#if PAGE_SIZE < SZ_64K
> +
> +/*
> + * Limit contiguous RDMA Read sink allocations to 64KB
> + * (order-4 on 4KB-page systems). Higher orders risk
> + * allocation failure under __GFP_NORETRY, which would
> + * negate the benefit of the contiguous fast path.
> + */
> +#define SVC_RDMA_CONTIG_MAX_ORDER get_order(SZ_64K)
Isn't the limit really an order and thus grows with the page size,
instead of based on a fixed size?
> + o = get_order(nr_pages << PAGE_SHIFT);
> + if (o > SVC_RDMA_CONTIG_MAX_ORDER)
> + o = SVC_RDMA_CONTIG_MAX_ORDER;
Use min()?
next prev parent reply other threads:[~2026-03-17 14:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-13 19:41 [PATCH v3 0/4] RDMA/rw: Fix MR pool exhaustion in bvec RDMA READ path Chuck Lever
2026-03-13 19:41 ` [PATCH v3 1/4] RDMA/rw: Fall back to direct SGE on MR pool exhaustion Chuck Lever
2026-03-17 14:24 ` Christoph Hellwig
2026-03-13 19:41 ` [PATCH v3 2/4] RDMA/rw: Fix MR pool exhaustion in bvec RDMA READ path Chuck Lever
2026-03-17 14:25 ` Christoph Hellwig
2026-03-13 19:42 ` [PATCH v3 3/4] SUNRPC: Add svc_rqst_page_release() helper Chuck Lever
2026-03-17 14:26 ` Christoph Hellwig
2026-03-13 19:42 ` [PATCH v3 4/4] svcrdma: Use contiguous pages for RDMA Read sink buffers Chuck Lever
2026-03-17 14:28 ` Christoph Hellwig [this message]
2026-03-17 15:26 ` Chuck Lever
2026-03-16 20:15 ` [PATCH v3 0/4] RDMA/rw: Fix MR pool exhaustion in bvec RDMA READ path Leon Romanovsky
2026-03-16 20:24 ` Chuck Lever
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