On Fri, May 15, 2015 at 01:03:02PM +0800, Wanpeng Li wrote: > On Thu, May 14, 2015 at 12:29:21PM -0700, Andrew Honig wrote: > >> > >> BTW, what is the purpose of this series. If I understand it correctly, you only want to > >> use the in-kernel lapic and leave the others (pic, ioapic) in userspace, what is the > >> benefit of it? > > > >The purpose is to achieve the security benefit of removing some of the > >interrupt handling into userspace, without incurring a significant > >performance penalty. If you move the entire IRQCHIP into userspace, > >we've seen perf impacts from 15-200% depending on the workload. With > >this patch series, we're seeing perf penalty <1% on our tests (TCP_RR > > Why keep pic and ioapic in kernel space not get obvious benefit, what's > the bottleneck? It's the other way around. The PIC and IOAPIC are going up to userspace, and the APICs are staying in the kernel. > > Regards, > Wanpeng Li > > >latency, TCP throughput, and Disk I/O). See > >(https://lwn.net/Articles/619332/) > > > >> > >> Thanks, > >> Feng > >> > >>> > >-- > >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 -- 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
