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. 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). Dacapo without individual addr invvpid: real 1m25.406s user 4m59.315s sys 1m25.406s Dacapo with individual addr invvpid: real 1m4.421s user 3m47.150s sys 0m1.592s -- vanilla kernel build without individual addr invvpid: real 16m42.571s user 13m28.975s sys 2m54.487s vanilla kernel build with individual addr invvpid: real 15m45.789s user 12m25.691s sys 2m44.806s -- vanilla kernel build (-j8) without individual addr invvpid: real 10m32.276s user 33m47.687s sys 5m37.725s vanilla kernel build (-j8) with individual addr invvpid: real 8m29.789s user 28m12.850s sys 4m34.353s In all cases using individual address invalidation outperforms single context ones regarding wall time. Comments? [1] http://dacapobench.org/ Thanks, Davidlohr -- 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
