> On May 31, 2019, at 11:48 AM, Andy Lutomirski <l...@amacapital.net> wrote: > > >> On May 30, 2019, at 11:36 PM, Nadav Amit <na...@vmware.com> wrote: >> >> cpu_tlbstate is mostly private and only the variable is_lazy is shared. >> This causes some false-sharing when TLB flushes are performed. >> >> Break cpu_tlbstate intro cpu_tlbstate and cpu_tlbstate_shared, and mark >> each one accordingly. > > At some point we’ll want to do a better job with our PV flush code, and I > suspect we’ll end up with more of this shared again.
In the usual use-case, when you flush the TLB, will you write something to cpu_tlbstate that should be visible to other cores? I don’t see why, even if PV is used. Anyhow, I was always under the impression that PV should not punish bare-metal. The other option is to take cpu_tlbstate and rearrange it so the shared stuff will not be next to the private. I just don’t know how to do it without making an assumption of the cacheline size.
