[v2] trace: Immediately apply per-vCPU state changes if a vCPU is being created

[Qemu-devel] [PATCH v2] trace: Immediately apply per-vCPU state changes if a vCPU is being created

Lluís Vilanova posted 1 patch 6 years, 7 months ago

Diff against v1 v2
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git fetch https://github.com/patchew-project/qemu tags/patchew/150525662577.19850.13767570977540117247.stgit@frigg.lan

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trace/control-target.c |   18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

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[Qemu-devel] [PATCH v2] trace: Immediately apply per-vCPU state changes if a vCPU is being created

Posted by Lluís Vilanova 6 years, 7 months ago

Right now, function trace_event_set_vcpu_state_dynamic() asynchronously enables
events in the case a vCPU is executing TCG code. If the vCPU is being created
this makes some events like "guest_cpu_enter" to not be traced.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Reviewed-by: Emilio G. Cota <cota@braap.org>
---

Changes in v2
=============

* Use RUN_ON_CPU_NULL [Emilio G. Cota].
* Rebase on fcea73709b.
---
 trace/control-target.c |   18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/trace/control-target.c b/trace/control-target.c
index 4e36101997..706b2cee9d 100644
--- a/trace/control-target.c
+++ b/trace/control-target.c
@@ -88,13 +88,17 @@ void trace_event_set_vcpu_state_dynamic(CPUState *vcpu,
             clear_bit(vcpu_id, vcpu->trace_dstate_delayed);
             (*ev->dstate)--;
         }
-        /*
-         * Delay changes until next TB; we want all TBs to be built from a
-         * single set of dstate values to ensure consistency of generated
-         * tracing code.
-         */
-        async_run_on_cpu(vcpu, trace_event_synchronize_vcpu_state_dynamic,
-                         RUN_ON_CPU_NULL);
+        if (vcpu->created) {
+            /*
+             * Delay changes until next TB; we want all TBs to be built from a
+             * single set of dstate values to ensure consistency of generated
+             * tracing code.
+             */
+            async_run_on_cpu(vcpu, trace_event_synchronize_vcpu_state_dynamic,
+                             RUN_ON_CPU_NULL);
+        } else {
+            trace_event_synchronize_vcpu_state_dynamic(vcpu, RUN_ON_CPU_NULL);
+        }
     }
 }

Re: [Qemu-devel] [PATCH v2] trace: Immediately apply per-vCPU state changes if a vCPU is being created

Posted by Stefan Hajnoczi 6 years, 7 months ago

On Wed, Sep 13, 2017 at 01:50:25AM +0300, Lluís Vilanova wrote:
> Right now, function trace_event_set_vcpu_state_dynamic() asynchronously enables
> events in the case a vCPU is executing TCG code. If the vCPU is being created
> this makes some events like "guest_cpu_enter" to not be traced.
> 
> Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
> Reviewed-by: Emilio G. Cota <cota@braap.org>
> ---
> 
> Changes in v2
> =============
> 
> * Use RUN_ON_CPU_NULL [Emilio G. Cota].
> * Rebase on fcea73709b.
> ---
>  trace/control-target.c |   18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)

Thanks, applied to my tracing tree:
https://github.com/stefanha/qemu/commits/tracing

Stefan