From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH] IB/mlx5: Expose correct max_sge_rd limit Date: Thu, 7 Apr 2016 10:05:24 +0300 Message-ID: <570606B4.5040402@grimberg.me> References: <1459440205-25208-1-git-send-email-sagig@grimberg.me> <20160401000426.GF2670@leon.nu> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160401000426.GF2670-2ukJVAZIZ/Y@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Doug Ledford Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Matan Barak , Leon Romanovsky List-Id: linux-rdma@vger.kernel.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 >> Tested-by: Christoph Hellwig >> Signed-off-by: Sagi Grimberg > > Thanks Sagi, > > Excellent catch, the same as in commit: a5e4ba334e2 > ("mlx4: Expose correct max_sge_rd limit") > > Signed-off-by: Leon Romanovsky Doug, this is stable material, can we get it to 4.6-rc and place a stable tag on it? Thanks, Sagi. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html