[PATCH v3 3/3] KVM: trace kvm_halt_poll_ns grow/shrink

[Wanpeng Li]

Tracepoint for dynamic halt_pool_ns, fired on every potential change.

Signed-off-by: Wanpeng Li <wanpeng...@hotmail.com>
---
 include/trace/events/kvm.h | 30 ++++++++++++++++++++++++++++++
 virt/kvm/kvm_main.c        |  8 ++++++--
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
index a44062d..75ddf80 100644
--- a/include/trace/events/kvm.h
+++ b/include/trace/events/kvm.h
@@ -356,6 +356,36 @@ TRACE_EVENT(
                  __entry->address)
 );
 
+TRACE_EVENT(kvm_halt_poll_ns,
+       TP_PROTO(bool grow, unsigned int vcpu_id, int new, int old),
+       TP_ARGS(grow, vcpu_id, new, old),
+
+       TP_STRUCT__entry(
+               __field(bool, grow)
+               __field(unsigned int, vcpu_id)
+               __field(int, new)
+               __field(int, old)
+       ),
+
+       TP_fast_assign(
+               __entry->grow           = grow;
+               __entry->vcpu_id        = vcpu_id;
+               __entry->new            = new;
+               __entry->old            = old;
+       ),
+
+       TP_printk("vcpu %u: halt_pool_ns %d (%s %d)",
+                       __entry->vcpu_id,
+                       __entry->new,
+                       __entry->grow ? "grow" : "shrink",
+                       __entry->old)
+);
+
+#define trace_kvm_halt_poll_ns_grow(vcpu_id, new, old) \
+       trace_kvm_halt_poll_ns(true, vcpu_id, new, old)
+#define trace_kvm_halt_poll_ns_shrink(vcpu_id, new, old) \
+       trace_kvm_halt_poll_ns(false, vcpu_id, new, old)
+
 #endif
 
 #endif /* _TRACE_KVM_MAIN_H */
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1ed02d1..a4b7eb9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1918,8 +1918,9 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_mark_page_dirty);
 
 static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
 {
-       int val = vcpu->halt_poll_ns;
+       int old, val;
 
+       old = val = vcpu->halt_poll_ns;
        /* 500us step */
        if (val == 0 && halt_poll_ns_grow)
                val = 500000;
@@ -1927,18 +1928,21 @@ static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
                val *= halt_poll_ns_grow;
 
        vcpu->halt_poll_ns = val;
+       trace_kvm_halt_poll_ns_grow(vcpu->vcpu_id, val, old);
 }
 
 static void shrink_halt_poll_ns(struct kvm_vcpu *vcpu)
 {
-       int val = vcpu->halt_poll_ns;
+       int old, val;
 
+       old = val = vcpu->halt_poll_ns;
        if (halt_poll_ns_shrink == 0)
                val = 0;
        else
                val /= halt_poll_ns_shrink;
 
        vcpu->halt_poll_ns = val;
+       trace_kvm_halt_poll_ns_shrink(vcpu->vcpu_id, val, old);
 }
 
 static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
-- 
1.9.1

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