On 07/09/2019 07:45 PM, Peter Zijlstra wrote:
+* config:Actually this field won't be used by the perf core
+*as this event doesn't have a perf counter.
+* sample_period: Same as above.
If it's unused; why do we need to set it at all?
OK, we'll
On 07/09/2019 08:19 PM, Peter Zijlstra wrote:
For the lbr feature, could we thought of it as first come, first served?
For example, if we have 2 host threads who want to use lbr at the same time,
I think one of them would simply fail to use.
So if guest first gets the lbr, host wouldn't take o
On Tue, Jul 09, 2019 at 07:34:26PM +0800, Wei Wang wrote:
> > But what about the counter scheduling rules;
>
> The counter is emulated independent of the lbr emulation.
> > what happens when a CPU
> > event claims the LBR before the task event can claim it? CPU events have
> > precedence over ta
On Mon, Jul 08, 2019 at 09:23:15AM +0800, Wei Wang wrote:
> +int intel_pmu_enable_save_guest_lbr(struct kvm_vcpu *vcpu)
> +{
> + struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
> + struct perf_event *event;
> +
> + /*
> + * The main purpose of this perf event is to have the host perf core
On 07/09/2019 05:39 PM, Peter Zijlstra wrote:
On Tue, Jul 09, 2019 at 11:04:21AM +0800, Wei Wang wrote:
On 07/08/2019 10:48 PM, Peter Zijlstra wrote:
*WHY* does the host need to save/restore? Why not make VMENTER/VMEXIT do
this?
Because the VMX transition is much more frequent than the vCPU sw
On Tue, Jul 09, 2019 at 11:04:21AM +0800, Wei Wang wrote:
> On 07/08/2019 10:48 PM, Peter Zijlstra wrote:
> > *WHY* does the host need to save/restore? Why not make VMENTER/VMEXIT do
> > this?
>
> Because the VMX transition is much more frequent than the vCPU switching.
> On SKL, saving 32 LBR en
On 07/08/2019 10:48 PM, Peter Zijlstra wrote:
On Mon, Jul 08, 2019 at 09:23:15AM +0800, Wei Wang wrote:
From: Like Xu
This patch adds support to enable/disable the host side save/restore
This patch should be disqualified on Changelog alone...
Documentation/process/submitting-patches.rst:i
On Mon, Jul 08, 2019 at 09:23:15AM +0800, Wei Wang wrote:
> From: Like Xu
>
> This patch adds support to enable/disable the host side save/restore
This patch should be disqualified on Changelog alone...
Documentation/process/submitting-patches.rst:instead of "[This patch] makes
xyzzy do frot
From: Like Xu
This patch adds support to enable/disable the host side save/restore
for the guest lbr stack on vCPU switching. To enable that, the host
creates a perf event for the vCPU, and the event attributes are set
to the user callstack mode lbr so that all the conditions are meet in
the host
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