From 3f7a06d68337171fef9f8e7621a6d73777385619 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Wed, 31 Oct 2012 12:38:31 -0400 Subject: [PATCH] xen/mmu: Use Xen specific TLB flush instead of the generic one. commit 95a7d76897c1e7243d4137037c66d15cbf2cce76 upstream. As Mukesh explained it, the MMUEXT_TLB_FLUSH_ALL allows the hypervisor to do a TLB flush on all active vCPUs. If instead we were using the generic one (which ends up being xen_flush_tlb) we end up making the MMUEXT_TLB_FLUSH_LOCAL hypercall. But before we make that hypercall the kernel will IPI all of the vCPUs (even those that were asleep from the hypervisor perspective). The end result is that we needlessly wake them up and do a TLB flush when we can just let the hypervisor do it correctly. This patch gives around 50% speed improvement when migrating idle guest's from one host to another. Oracle-bug: 14630170 Tested-by: Jingjie Jiang Suggested-by: Mukesh Rathor Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman --- arch/x86/xen/mmu.c | 21 ++++++++++++++++++++- include/trace/events/xen.h | 8 ++++++++ 2 files changed, 28 insertions(+), 1 deletion(-) diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 5141d808e751..dde1a3fc465a 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -1215,6 +1215,25 @@ unsigned long xen_read_cr2_direct(void) return this_cpu_read(xen_vcpu_info.arch.cr2); } +void xen_flush_tlb_all(void) +{ + struct mmuext_op *op; + struct multicall_space mcs; + + trace_xen_mmu_flush_tlb_all(0); + + preempt_disable(); + + mcs = xen_mc_entry(sizeof(*op)); + + op = mcs.args; + op->cmd = MMUEXT_TLB_FLUSH_ALL; + MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); + + xen_mc_issue(PARAVIRT_LAZY_MMU); + + preempt_enable(); +} static void xen_flush_tlb(void) { struct mmuext_op *op; @@ -2366,7 +2385,7 @@ int xen_remap_domain_mfn_range(struct vm_area_struct *vma, err = 0; out: - flush_tlb_all(); + xen_flush_tlb_all(); return err; } diff --git a/include/trace/events/xen.h b/include/trace/events/xen.h index 15ba03bdd7c6..d06b6da5c1e3 100644 --- a/include/trace/events/xen.h +++ b/include/trace/events/xen.h @@ -377,6 +377,14 @@ DECLARE_EVENT_CLASS(xen_mmu_pgd, DEFINE_XEN_MMU_PGD_EVENT(xen_mmu_pgd_pin); DEFINE_XEN_MMU_PGD_EVENT(xen_mmu_pgd_unpin); +TRACE_EVENT(xen_mmu_flush_tlb_all, + TP_PROTO(int x), + TP_ARGS(x), + TP_STRUCT__entry(__array(char, x, 0)), + TP_fast_assign((void)x), + TP_printk("%s", "") + ); + TRACE_EVENT(xen_mmu_flush_tlb, TP_PROTO(int x), TP_ARGS(x), -- 2.39.5