> On Aug 27, 2019, at 4:07 PM, Andy Lutomirski <l...@kernel.org> wrote: > > On Fri, Aug 23, 2019 at 11:13 PM Nadav Amit <na...@vmware.com> wrote: >> When a shootdown is initiated, the initiating CPU has cycles to burn as >> it waits for the responding CPUs to receive the IPI and acknowledge it. >> In these cycles it is better to flush the user page-tables using >> INVPCID, instead of deferring the TLB flush. >> >> The best way to figure out whether there are cycles to burn is arguably >> to expose from the SMP layer when an acknowledgment is received. >> However, this would break some abstractions. >> >> Instead, use a simpler solution: the initiating CPU of a TLB shootdown >> would not defer PTI flushes. It is not always a win, relatively to >> deferring user page-table flushes, but it prevents performance >> regression. >> >> Signed-off-by: Nadav Amit <na...@vmware.com> >> --- >> arch/x86/include/asm/tlbflush.h | 1 + >> arch/x86/mm/tlb.c | 10 +++++++++- >> 2 files changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/include/asm/tlbflush.h >> b/arch/x86/include/asm/tlbflush.h >> index da56aa3ccd07..066b3804f876 100644 >> --- a/arch/x86/include/asm/tlbflush.h >> +++ b/arch/x86/include/asm/tlbflush.h >> @@ -573,6 +573,7 @@ struct flush_tlb_info { >> unsigned int initiating_cpu; >> u8 stride_shift; >> u8 freed_tables; >> + u8 shootdown; > > I find the name "shootdown" to be confusing. How about "more_than_one_cpu”?
I think the current semantic is more of “includes remote cpus”. How about calling it “local_only”, and negating its value?