I'm interested too. Muli Ben-Yehuda wrote: > If there's interest, I'll be happy to give this talk I'll be giving at > OLS '07 at Haifux as well. > > The Price of Safety: Evaluating IOMMU Performance > > IOMMUs, "IO Memory Management Units", are hardware devices that > translate device DMA addresses to machine addresses. Isolation capable > IOMMUs perform a valuable system service, preventing rogue devices > from performing errant or malicious DMAs, thereby substantially > increasing the system's reliability and availability. Without an > IOMMU, a peripheral device could be programmed to overwrite any part > of the system's memory. An isolation capable IOMMU restricts a device > so that it can only access parts of memory it has been explicitly > granted access to. Operating systems utilize IOMMUs to isolate device > drivers; hypervisors utilize IOMMUs to grant secure direct hardware > access to virtual machines. With the imminent publication of the > PCI-SIG's IO Virtualization standard, as well as Intel and AMD's > introduction of isolation capable IOMMUs in all new servers, IOMMUs > will become ubiquitous. > > IOMMUs can impose a performance penalty due to the extra memory > accesses required to perform DMA operations. The exact performance > degradation depends on the IOMMU design, its caching architecture, the > way it is programmed and the workload. In this paper, we present the > performance characteristics of the Calgary and DART IOMMUs in Linux, > both on bare metal and hypervisors. We measure the throughput and CPU > utilization of several IO workloads with and without an IOMMU and > analyze the results. We then discuss potential strategies for > mitigating the IOMMU's costs. We conclude by presenting a set of > optimizations we have implemented and the resulting performance > improvements. > > Cheers, > Muli > > --------------------------------------------------------------------- > Haifa Linux Club Mailing List (http://www.haifux.org) > To unsub send an empty message to [EMAIL PROTECTED] > > >
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