From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Steve Wise" Subject: RE: [PATCH 7/9] IB/core: generic RDMA READ/WRITE API Date: Tue, 1 Mar 2016 09:47:24 -0600 Message-ID: <006101d173d1$a63a1b00$f2ae5100$@opengridcomputing.com> 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> <56D55EB3.2050707@dev.mellanox.co.il> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56D55EB3.2050707-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org> Content-Language: en-us Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: 'Sagi Grimberg' , 'Christoph Hellwig' Cc: 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 > -----Original Message----- > From: Sagi Grimberg [mailto:sagig-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org] > Sent: Tuesday, March 01, 2016 3:20 AM > 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 > Subject: Re: [PATCH 7/9] IB/core: generic RDMA READ/WRITE API > > > >>>> + 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). I mean for iWARP, we can do RDMA WRITE operations w/o a MR, if the ib_sge is small enough given the device max send depth. -- 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