On Tue, May 25, 2021, Stamatis, Ilias wrote: > Hmm, this patch actually still removes the caching and introduces a small > performance overhead. For example if neither L1 nor L2 are scaled it will > still do a vmwrite for every L2 entry/write. True, but there is an ocean of difference between the relative performance of vmx_vcpu_load_vmcs() and a nested transition. vmx_vcpu_load_vmcs() is also called much more frequently. > So do we want to get rid of decache_tsc_multiplier() but keep > vmx->current_tsc_ratio and do the check inside write_tsc_multiplier()? Or > alternatively delete vmx->current_tsc_ratio too and have > write_tsc_multiplier() receive 2 parameters, one of the old multiplier and > one of the new? My vote is to kill it, eat the barely-noticeable perf hit on nVMX, and tackle the aggressive VMCS shadowing in a separate series.
