On 01/20/2012 05:02 PM, Benjamin Herrenschmidt wrote: > >> With Topaz, interrupts go directly to guests and we don't want to require a >> trap/hcall to do an IACK, as that adds potentially thousands of cycles of >> latency to every interrupt. >> >> As you know, with external proxy interrupts are acknowledged by the >> hardware and it becomes problematic to replay the interrupt in >> the context of lazy EE when interrupts are re-enabled. The interrupt >> will not fire again when you enable EE. > > So you have a broken HW and broken HV design to start with ... :-)
That "breakage" significantly reduces the overhead of handling interrupts in a guest, since we don't need to involve the hypervisor (at least on the entry side -- there's a hack to avoid it on EOI as well, though that involves exposing some MPIC registers directly; users can decide whether it's worth enabling for their use case). -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
