On Friday 09 May 2014 09:32:26 Bjorn Helgaas wrote: > > There are people who care deeply about the performance of IOMMU API > > map/unmap. It isn't used *just* for virtual machines any more. See > > drivers/infiniband/hw/usnic/usnic_uiom.c for example. > > Of course we should care about IOMMU API performance. We should also > care about interface consistency, and it seems there's a tradeoff in > this case. I said "relatively" because I expect map/unmap to be less > frequent than read/write operations that use the mapping. I don't > know anything about infiniband, so maybe that assumption is false > there. In most drivers using the streaming DMA API, every mapping is used exactly once. Think of network or block drivers: they rarely send the same data twice to the device, and it usually comes from or goes to some user space buffer. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
