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

[Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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On 04/07/2016 03:05 AM, Sagi Grimberg wrote:
> 
> 
> 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.

Done, thanks.

-- 
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
              GPG KeyID: 0E572FDD



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