Re: [PATCH] IB/mlx5: Expose correct max_sge_rd limit

[Sagi Grimberg <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>]

On 01/04/16 03:04, Leon Romanovsky wrote:
> On Thu, Mar 31, 2016 at 07:03:25PM +0300, Sagi Grimberg wrote:
>> mlx5 devices (Connect-IB, ConnectX-4, ConnectX-4-LX) has a limitation
>> where rdma read work queue entries cannot exceed 512 bytes.
>> A rdma_read wqe needs to fit in 512 bytes:
>> - wqe control segment (16 bytes)
>> - rdma segment (16 bytes)
>> - scatter elements (16 bytes each)
>>
>> So max_sge_rd should be: (512 - 16 - 16) / 16 = 30.
>>
>> Reported-by: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
>> Tested-by: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
>> Signed-off-by: Sagi Grimberg <sagig-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
>
> Thanks Sagi,
>
> Excellent catch, the same as in commit: a5e4ba334e2
> ("mlx4: Expose correct max_sge_rd limit")
>
> Signed-off-by: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

Doug, this is stable material, can we get it to 4.6-rc
and place a stable tag on it?

Thanks,
Sagi.
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