On Tue, Jun 27, 2017 at 07:07:08PM +0300, Sagi Grimberg wrote: > > >Go back and browse the end of the thread: there's no need to change > >xprtrdma, and maybe no need to change the others either. > > I think there is, even with inline, xprtrdma dma maps the immediate > buffers, also the message head and tail so unmapping these buffers > without waiting for the send completion would trigger a IOMMU access > error (the HCA (re)tries to access an already unmapped buffer). Yes, that is an excellent observation. When using the local rdma lkey you still need to ensure the linux API DMA map remains until completion. send completion mitigation is still possible, if it is OK for the backing pages to remain, but I think a more sophisticated strategy is needed - eg maybe push some kind of NOP through the send q after a timer or only complete when the last available work is stuffed or something. Jason -- 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
