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
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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;
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...
Steve.
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