On 09/06/2012 12:54 AM, Davidlohr Bueso wrote: > On Mon, 2012-09-03 at 12:11 +0300, Avi Kivity wrote: >> On 09/03/2012 02:27 AM, Davidlohr Bueso wrote: >> > On Fri, 2012-08-31 at 14:37 -0300, Marcelo Tosatti wrote: >> >> On Fri, Aug 31, 2012 at 06:10:48PM +0200, Davidlohr Bueso wrote: >> >> > For processors that support VPIDs we should invalidate the page table entry >> >> > specified by the lineal address. For this purpose add support for individual >> >> > address invalidations. >> >> >> >> Not necessary - a single context invalidation is performed through >> >> KVM_REQ_TLB_FLUSH. >> > >> > Since vpid_sync_context() supports both single and all-context vpid >> > invalidations, wouldn't it make sense to also add individual address >> > ones as well, supporting further granularity? >> >> It might. Do you have benchmarks supporting this? >> > > I ran two benchmarks: Java Dacapo[1] Sunflow (renders a set of images > using ray tracing) and a vanilla 3.2 kernel build (with 1 job and -j8). > > The host configuration is an Intel i7-2635QM (4 cores + HT) with 4Gb RAM > running Linus's latest and only running standard system daemons. For KVM > I disabled EPT. That's not very interesting. In all real machines, if you have VPID you also have EPT. Intel are unlikely to produce a processor without EPT. > The guest configuration is a 64bit 4 core 4Gb RAM, running Linux 3.2 > (debian) and only running the benchmark. > > All results represent the mean of 5 runs, with time(1). The results are impressive, but lack real-world relevance. Individual-address invalidation isn't very useful with EPT, since we let the guest issue INVLPG itself and otherwise don't bother with guest page tables. Individual-address INVEPT would probably be more useful, but there is no such instruction variant. -- error compiling committee.c: too many arguments to function -- 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
