Re: [PATCH v3 4/4] svcrdma: Use contiguous pages for RDMA Read sink buffers

Chuck Lever
2026-03-17T15:26:27Z

On Tue, Mar 17, 2026, at 10:28 AM, Christoph Hellwig wrote:
> On Fri, Mar 13, 2026 at 03:42:01PM -0400, Chuck Lever wrote:
>> +#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?

So on a platform with 16KB pages, an order-4 allocation request
(256KB) is still desirable for our purpose here?

--
Chuck Lever