I agree with you that changing kernel ABI is not necessary. I will follow your directions regarding a single allocation at start.
Regards, Mirek -----Original Message----- From: Roland Dreier [mailto:rdre...@cisco.com] Sent: Friday, August 06, 2010 5:58 PM To: Walukiewicz, Miroslaw Cc: linux-rdma@vger.kernel.org Subject: Re: {RFC] ibv_post_send()/ibv_post_recv() kernel path optimizations > The proposed path optimization is removing of dynamic allocations > by redefining a structure definition passed to kernel. > To > > struct ibv_post_send { > __u32 command; > __u16 in_words; > __u16 out_words; > __u64 response; > __u32 qp_handle; > __u32 wr_count; > __u32 sge_count; > __u32 wqe_size; > struct ibv_kern_send_wr send_wr[512]; > }; I don't see how this can possibly work. Where does the scatter/gather list go if you make this have a fixed size array of send_wr? Also I don't see why you need to change the user/kernel ABI at all to get rid of dynamic allocations... can't you just have the kernel keep a cached send_wr allocation (say, per user context) and reuse that? (ie allocate memory but don't free the first time into post_send, and only reallocate if a bigger send request comes, and only free when destroying the context) - R. -- Roland Dreier <rola...@cisco.com> || For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/index.html -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
