From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 2/5] IB/core: Add max_sge argument to rdma_rw_ctx_init() Date: Tue, 28 Jun 2016 17:42:35 +0200 Message-ID: <20160628154235.GA2843@lst.de> References: <419391ba-0c39-11ce-f249-84b428dc73d5@sandisk.com> <20160628115206.GB28113@lst.de> <7fbd81ae-4b0d-4f8b-18ac-7efcf0dd4d61@sandisk.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <7fbd81ae-4b0d-4f8b-18ac-7efcf0dd4d61-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Bart Van Assche Cc: Christoph Hellwig , Doug Ledford , Sagi Grimberg , "Nicholas A. Bellinger" , Parav Pandit , Laurence Oberman , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-rdma@vger.kernel.org On Tue, Jun 28, 2016 at 02:37:29PM +0200, Bart Van Assche wrote: > The memory needed for QP buffers strongly depends on max_send_sge and > max_recv_sge. Using a large value for max_send_sge and/or max_recv_sge for > all drivers would increase the memory consumption for drivers that only > submit RDMA requests with a low number of SG elements. Using a small value > for max_send_sge and/or max_recv_sge would result in a performance decrease > for drivers that benefit from large max_send_sge and/or max_recv_sge > values. This is why I think that drivers should have the freedom to chose > the max_send_sge and max_recv_sge values. No problem with that - but please configure it on the QP as part of the qp_init_attr structure instead of passing it to every RDMA READ/WRITE call. -- 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