Matt Thomas comments as;
More systems are getting larger numbers of TLB entries. ...Invalidate all becomes expensive when your TLBs get very large as does discarding live entries.
My own conclusion is that invalidating "live entries" on ASID wrap (=generation bump), if any, makes little matter since "live PTEs" are likely in cache. TLBrefill operation is very cheap in that case as refill-target PTEs are already fetched and stored somewhere in primary Dcache or at worst in multi-MB L2 cache given modestly loaded system runtime. Toru Nishimura / ALKYL Technology