> -----Original Message----- > From: linux-nfs-owner@xxxxxxxxxxxxxxx [mailto:linux-nfs-owner@xxxxxxxxxxxxxxx] On Behalf Of Jason Gunthorpe > Sent: Tuesday, July 21, 2015 5:55 PM > To: Steve Wise > Cc: 'Tom Talpey'; 'Chuck Lever'; linux-rdma@xxxxxxxxxxxxxxx; linux-nfs@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v3 05/15] xprtrdma: Remove last ib_reg_phys_mr() call site > > On Tue, Jul 21, 2015 at 05:41:22PM -0500, Steve Wise wrote: > > On 7/20/2015 5:42 PM, Jason Gunthorpe wrote: > > >On Mon, Jul 20, 2015 at 05:41:27PM -0500, Steve Wise wrote: > > >>>B) why bother to check? Are machines with <4GB interesting, and worth > > >>>supporting a special optimization? > > >>No, but cxgb3 is still interesting to user applications, and perhaps NFSRDMA using FRMRs. > > >Doesn't look like the NFS client will work. It requires an all > > >physical memory lkey for SEND and RECV buffers.. > > > > > >Jason > > > > Looks like cxgb3 supports LOCAL_DMA_LKEY and MEM_MGT_EXTENSIONS so dma mrs > > aren't required for NFSRDMA: > > > > t4:~/linux-2.6/drivers/infiniband/hw/cxgb3 # grep IB_DEVICE_ iwch_provider.c > > strlcpy(dev->ibdev.name, "cxgb3_%d", IB_DEVICE_NAME_MAX); > > dev->device_cap_flags = IB_DEVICE_LOCAL_DMA_LKEY | > > IB_DEVICE_MEM_WINDOW | > > IB_DEVICE_MEM_MGT_EXTENSIONS; > > Neat. Is the dma_mask set properly (I don't see any set at all)? > iw_cxgb3 isn't a PCI driver. It sits on top of cxgb3 which is the pci device driver and calls pci_set_dma_mask(). > > So cxgb3 can still support NFSRDMA and user verbs w/o get_dma_mr(). I'll > > submit a patch soon to only support get_dma_mr() if unsigned long is 4 > > bytes... > > So, NFS and RDS seem to be the only iWarp compatible ULPs? > > NFS has worked, and will continue to work with the global lkey. > > RDS looks like it relies on an insecure all physical rkey, so it won't > work until that is fixed. > > So, I'd just use sizeof(physaddr_t) > 4 as the test. The only people > that could be impacted are RDS users using distro kernels on machines > with less than 4G of ram. I somehow doubt there are any of those... > > Jason > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
