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-rw-r--r--Documentation/virt/kvm/api.rst19
1 files changed, 14 insertions, 5 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 11e00a46c610..98a283930307 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -5657,7 +5657,8 @@ 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_MAX KVM_STATS_UNIT_CYCLES
+ #define KVM_STATS_UNIT_BOOLEAN (0x4 << KVM_STATS_UNIT_SHIFT)
+ #define KVM_STATS_UNIT_MAX KVM_STATS_UNIT_BOOLEAN
#define KVM_STATS_BASE_SHIFT 8
#define KVM_STATS_BASE_MASK (0xF << KVM_STATS_BASE_SHIFT)
@@ -5702,14 +5703,13 @@ Bits 0-3 of ``flags`` encode the type:
by the ``hist_param`` field. The range of the Nth bucket (1 <= N < ``size``)
is [``hist_param``*(N-1), ``hist_param``*N), while the range of the last
bucket is [``hist_param``*(``size``-1), +INF). (+INF means positive infinity
- value.) The bucket value indicates how many samples fell in the bucket's range.
+ value.)
* ``KVM_STATS_TYPE_LOG_HIST``
The statistic is reported as a logarithmic histogram. The number of
buckets is specified by the ``size`` field. The range of the first bucket is
[0, 1), while the range of the last bucket is [pow(2, ``size``-2), +INF).
Otherwise, The Nth bucket (1 < N < ``size``) covers
- [pow(2, N-2), pow(2, N-1)). The bucket value indicates how many samples fell
- in the bucket's range.
+ [pow(2, N-2), pow(2, N-1)).
Bits 4-7 of ``flags`` encode the unit:
@@ -5724,6 +5724,15 @@ Bits 4-7 of ``flags`` encode the unit:
It indicates that the statistics data is used to measure time or latency.
* ``KVM_STATS_UNIT_CYCLES``
It indicates that the statistics data is used to measure CPU clock cycles.
+ * ``KVM_STATS_UNIT_BOOLEAN``
+ It indicates that the statistic will always be either 0 or 1. Boolean
+ statistics of "peak" type will never go back from 1 to 0. Boolean
+ statistics can be linear histograms (with two buckets) but not logarithmic
+ histograms.
+
+Note that, in the case of histograms, the unit applies to the bucket
+ranges, while the bucket value indicates how many samples fell in the
+bucket's range.
Bits 8-11 of ``flags``, together with ``exponent``, encode the scale of the
unit:
@@ -5746,7 +5755,7 @@ the corresponding statistics data.
The ``bucket_size`` field is used as a parameter for histogram statistics data.
It is only used by linear histogram statistics data, specifying the size of a
-bucket.
+bucket in the unit expressed by bits 4-11 of ``flags`` together with ``exponent``.
The ``name`` field is the name string of the statistics data. The name string
starts at the end of ``struct kvm_stats_desc``. The maximum length including