From: Nadav Amit <namit@xxxxxxxxxx> Sent: Thursday, July 18, 2019 5:59 PM > > To improve TLB shootdown performance, flush the remote and local TLBs > concurrently. Introduce flush_tlb_multi() that does so. Introduce > paravirtual versions of flush_tlb_multi() for KVM, Xen and hyper-v (Xen > and hyper-v are only compile-tested). > > While the updated smp infrastructure is capable of running a function on > a single local core, it is not optimized for this case. The multiple > function calls and the indirect branch introduce some overhead, and > might make local TLB flushes slower than they were before the recent > changes. > > Before calling the SMP infrastructure, check if only a local TLB flush > is needed to restore the lost performance in this common case. This > requires to check mm_cpumask() one more time, but unless this mask is > updated very frequently, this should impact performance negatively. > > Cc: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx> > Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> > Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx> > Cc: Sasha Levin <sashal@xxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: Borislav Petkov <bp@xxxxxxxxx> > Cc: x86@xxxxxxxxxx > Cc: Juergen Gross <jgross@xxxxxxxx> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > Cc: Andy Lutomirski <luto@xxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> > Cc: linux-hyperv@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx > Cc: kvm@xxxxxxxxxxxxxxx > Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx > Signed-off-by: Nadav Amit <namit@xxxxxxxxxx> > --- > arch/x86/hyperv/mmu.c | 10 +++--- > arch/x86/include/asm/paravirt.h | 6 ++-- > arch/x86/include/asm/paravirt_types.h | 4 +-- > arch/x86/include/asm/tlbflush.h | 8 ++--- > arch/x86/include/asm/trace/hyperv.h | 2 +- > arch/x86/kernel/kvm.c | 11 +++++-- > arch/x86/kernel/paravirt.c | 2 +- > arch/x86/mm/tlb.c | 47 ++++++++++++++++++--------- > arch/x86/xen/mmu_pv.c | 11 +++---- > include/trace/events/xen.h | 2 +- > 10 files changed, 62 insertions(+), 41 deletions(-) > For the Hyper-V parts -- Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
