Messages in this thread | | | Date | Mon, 18 Jul 2022 11:34:08 +0200 | Subject | Re: [PATCH] kvm: stats: tell userspace which values are boolean | From | Janis Schoetterl-Glausch <> |
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On 7/14/22 14:03, Paolo Bonzini wrote: > Some of the statistics values exported by KVM are always only 0 or 1. > It can be useful to export this fact to userspace so that it can track > them specially (for example by polling the value every now and then to > compute a % of time spent in a specific state). > > Therefore, add "boolean value" as a new "unit". While it is not exactly > a unit, it walks and quacks like one. In particular, using the type > would be wrong because boolean values could be instantaneous or peak > values (e.g. "is the rmap allocated?") or even two-bucket histograms > (e.g. "number of posted vs. non-posted interrupt injections"). > > Suggested-by: Amneesh Singh <natto@weirdnatto.in> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > Documentation/virt/kvm/api.rst | 6 ++++++ > arch/x86/kvm/x86.c | 2 +- > include/linux/kvm_host.h | 11 ++++++++++- > include/uapi/linux/kvm.h | 1 + > 4 files changed, 18 insertions(+), 2 deletions(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 11e00a46c610..48bf6e49a7de 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -5657,6 +5657,7 @@ by a string of size ``name_size``. > #define KVM_STATS_UNIT_BYTES (0x1 << KVM_STATS_UNIT_SHIFT) > #define KVM_STATS_UNIT_SECONDS (0x2 << KVM_STATS_UNIT_SHIFT) > #define KVM_STATS_UNIT_CYCLES (0x3 << KVM_STATS_UNIT_SHIFT) > + #define KVM_STATS_UNIT_BOOLEAN (0x4 << KVM_STATS_UNIT_SHIFT) > #define KVM_STATS_UNIT_MAX KVM_STATS_UNIT_CYCLES > > #define KVM_STATS_BASE_SHIFT 8
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> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 5088bd9f1922..811897dadcae 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -2083,6 +2083,7 @@ struct kvm_stats_header { > #define KVM_STATS_UNIT_BYTES (0x1 << KVM_STATS_UNIT_SHIFT) > #define KVM_STATS_UNIT_SECONDS (0x2 << KVM_STATS_UNIT_SHIFT) > #define KVM_STATS_UNIT_CYCLES (0x3 << KVM_STATS_UNIT_SHIFT) > +#define KVM_STATS_UNIT_BOOLEAN (0x4 << KVM_STATS_UNIT_SHIFT) > #define KVM_STATS_UNIT_MAX KVM_STATS_UNIT_CYCLES
Shouldn't KVM_STATS_UNIT_MAX be KVM_STATS_UNIT_BOOLEAN then?
The selftest has: TEST_ASSERT((pdesc->flags & KVM_STATS_UNIT_MASK) <= KVM_STATS_UNIT_MAX, "Unknown KVM stats unit"); > > #define KVM_STATS_BASE_SHIFT 8
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