Ab Haswell (also ab Core ix 4xxx) nutzbar durch PCID & INVPCID

Man benoetigt Haswell oder neuer (also ab Core ix 4xxx):

Laut

https://patchwork.kernel.org/patch/10035481/

reicht alleine das Feature PCID (ab Sandybridge) nicht aus, Zitat:

"PCIDs are generally available on Sandybridge and newer CPUs. However,
the accompanying INVPCID instruction did not become available until
Haswell (the ones with "v4", or called fourth-generation Core). This
instruction allows non-current-PCID TLB entries to be flushed without
switching CR3 and global pages to be flushed without a double
MOV-to-CR4.

Without INVPCID, PCIDs are much harder to use.

So, for now, fully disable PCIDs with KAISER when INVPCID is not
available. This is fixable, but it's an optimization that can be
performed later."

Das gilt fuer Linux, vermutlich aber auch fuer andere OS.