From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH 7/9] IB/core: generic RDMA READ/WRITE API Date: Tue, 1 Mar 2016 11:19:47 +0200 Message-ID: <56D55EB3.2050707@dev.mellanox.co.il> References: <1456784410-20166-1-git-send-email-hch@lst.de> <1456784410-20166-8-git-send-email-hch@lst.de> <56D4C615.5010202@opengridcomputing.com> <56D55A1B.6030902@dev.mellanox.co.il> <20160301091338.GA2208@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160301091338.GA2208-jcswGhMUV9g@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Christoph Hellwig Cc: Steve Wise , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sagig-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org, bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org, target-devel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org >>>> + if (rdma_rw_use_mr(qp->device, port_num)) { >>>> + ret = rdma_rw_init_mr_wrs(ctx, qp, port_num, sg, sg_offset, >>>> + remote_addr, rkey, dir); >>> >>> At some point I would like the iWARP IO to do no-mr for WRITE/dma_nents >>> == 1, and WRITE/dma_nents <= max_send_sge for the device. I think this >>> will help smaller iSER/NVMEF READ IOPs. I'm testing this out now on the >>> NVMEF code, which is slightly different. If it proves out to better the >>> performance, I'll post a follow-on patch... >> >> Is this possible given that pd->local_dma_lkey has only local >> permissions? > > I think he means NVMe / SCSI READ commands, which use RDMA WRITE. > For NVMe / SCSI WRITE commands that use RDMA READ all bets are off > for iWarp, but at least it supports READ W/ INVALIDATE. I interpreted "no-mr for WRITE/dma_nents == 1" as either RDMA_WRITE of RDMA_READ with a single dma entry (and that part I didn't understand). -- 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