On 11/16/2017 11:19 AM, Andrea Arcangeli wrote: > On Fri, Nov 10, 2017 at 11:31:50AM -0800, Dave Hansen wrote: >> Hugh Dickins also points out that PCIDs really have two distinct >> use-cases in the context of KAISER. The first way they can be used > I don't see why you try to retain such a minor optimization for newer > Intel chips when at the same you prevent KAISER to run with good > performance on older Intel chips like SandyBridge/IvyBridge which > would create a major performance regression for those two.
This was more straightforward to do. The other way requires having *TWO* PCID modes. So, we need to disambiguate the two modes in the existing infrastructure in addition to adding KAISER. Had I gone and done that, my fear was that we would be left with no usable PCIDs on *any* hardware. So, this was easier, I went and did it first, and I'd love to see someone add support for PCIDs on those older non-INVPCID systems. "Someone" may even be me, but it'll be in v2. Patches welcome before then. :)
