On Fri, Nov 04, 2016 at 01:55:12PM +0800, Yongji Xie wrote: > This keeps a per vcpu cache for recently page faulted MMIO entries. > On a page fault, if the entry exists in the cache, we can avoid some > time-consuming paths, for example, looking up HPT, locking HPTE twice > and searching mmio gfn from memslots, then directly call > kvmppc_hv_emulate_mmio(). > > In current implenment, we limit the size of cache to four. We think > it's enough to cover the high-frequency MMIO HPTEs in most case. > For example, considering the case of using virtio device, for virtio > legacy devices, one HPTE could handle notifications from up to > 1024 (64K page / 64 byte Port IO register) devices, so one cache entry > is enough; for virtio modern devices, we always need one HPTE to handle > notification for each device because modern device would use a 8M MMIO > register to notify host instead of Port IO register, typically the > system's configuration should not exceed four virtio devices per > vcpu, four cache entry is also enough in this case. Of course, if needed, > we could also modify the macro to a module parameter in the future. > > Signed-off-by: Yongji Xie <xyjxie@xxxxxxxxxxxxxxxxxx> Thanks, applied to kvm-ppc-next. Paul. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
