>hi, > Can someone briefly explain what the cr3-cache feature on intel VT >processors is and how it is used to improve performance in >paravirtualization.
In short, this is a unique Intel VT feature that supposed to save vmexit on cr3 switch. The vmexit operation is quite expensive at the moment (something like 2-5 ms!). PV kernels can use this feature by sharing memory between the host & the guest for the cr3 cache. When the guest wants to change cr3 it looks at the cache for a hit. If there is a hit there is no need to go out to the hypervisor and the guest continue to execute without the time consuming vmexit. You can check out Ingo's patch that does just it at http://people.redhat.com/mingo/kvm-paravirt-patches/kvm-paravirt-cr3-cac he.patch The down side is that the currently complex mmu implementation get's more complicated, while Intel & AMD will reduce the vmexit cost in the future. HTH, Dor Laor. > >Thanks > >Omar > > >----------------------------------------------------------------------- -- >Using Tomcat but need to do more? Need to support web services, security? >Get stuff done quickly with pre-integrated technology to make your job >easier. >Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo >http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=12164 2 >_______________________________________________ >kvm-devel mailing list >[email protected] >https://lists.sourceforge.net/lists/listinfo/kvm-devel ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier. Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ kvm-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kvm-devel
