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charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Jul 8, 2021 at 4:16 PM David Matlack wrote: > > On Thu, Jul 08, 2021 at 09:14:38PM +0000, David Matlack wrote: > > On Tue, Jul 06, 2021 at 06:03:48PM +0000, Jing Zhang wrote: > > > Add documentations for linear and logarithmic histogram statistics. > > > Add binary stats capability text which is missing during merge of > > > the binary stats patch. > > > > > > Signed-off-by: Jing Zhang > > > --- > > > Documentation/virt/kvm/api.rst | 36 +++++++++++++++++++++++++++++++--- > > > 1 file changed, 33 insertions(+), 3 deletions(-) > > > > > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > > index 3b6e3b1628b4..948d33c26704 100644 > > > --- a/Documentation/virt/kvm/api.rst > > > +++ b/Documentation/virt/kvm/api.rst > > > @@ -5171,6 +5171,9 @@ by a string of size ``name_size``. > > > #define KVM_STATS_TYPE_CUMULATIVE (0x0 << KVM_STATS_TYPE_SHIFT) > > > #define KVM_STATS_TYPE_INSTANT (0x1 << KVM_STATS_TYPE_SHIFT) > > > #define KVM_STATS_TYPE_PEAK (0x2 << KVM_STATS_TYPE_SHIFT) > > > + #define KVM_STATS_TYPE_LINEAR_HIST (0x3 << KVM_STATS_TYPE_SHIFT) > > > + #define KVM_STATS_TYPE_LOG_HIST (0x4 << KVM_STATS_TYPE_SHIFT) > > > + #define KVM_STATS_TYPE_MAX KVM_STATS_TYPE_LOG_HIST > > > > > > #define KVM_STATS_UNIT_SHIFT 4 > > > #define KVM_STATS_UNIT_MASK (0xF << KVM_STATS_UNIT_SHIFT) > > > @@ -5178,11 +5181,13 @@ 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_BASE_SHIFT 8 > > > #define KVM_STATS_BASE_MASK (0xF << KVM_STATS_BASE_SHIFT) > > > #define KVM_STATS_BASE_POW10 (0x0 << KVM_STATS_BASE_SHIFT) > > > #define KVM_STATS_BASE_POW2 (0x1 << KVM_STATS_BASE_SHIFT) > > > + #define KVM_STATS_BASE_MAX KVM_STATS_BASE_POW2 > > > > Should these FOO_MAX additions go in a separate commit too? > > > > > > > > struct kvm_stats_desc { > > > __u32 flags; > > > @@ -5214,6 +5219,22 @@ Bits 0-3 of ``flags`` encode the type: > > > represents a peak value for a measurement, for example the maximum number > > > of items in a hash table bucket, the longest time waited and so on. > > > The corresponding ``size`` field for this type is always 1. > > > + * ``KVM_STATS_TYPE_LINEAR_HIST`` > > > + The statistics data is in the form of linear histogram. The number of > > > + buckets is specified by the ``size`` field. The size of buckets is specified > > > + by the ``hist_param`` field. The range of the Nth bucket (1 <= N < ``size``) > > > > Using 1-based indexes is a little jarring but maybe that's just me :). > > > > > + 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 times the statistics data is in > > > + the bucket's range. > > > + * ``KVM_STATS_TYPE_LOG_HIST`` > > > + The statistics data is in the form of logarithmic histogram. The number of > > > + buckets is specified by the ``size`` field. The base of logarithm is > > > + specified by the ``hist_param`` field. The range of the Nth bucket (1 < N < > > > > Should 1 be 2 here? The first bucket uses a slightly differen formula as > > you mention in the next sentence. > > Oops I see you used "<" instead of "<=" so what you have is correct. I > think reordering the sentences would still be helpfull though. > Sure, will reorder the sentences as you suggested. > > > > Actually it may be clearer if you re-ordered the sentences a bit: > > > > The range of the first bucket is [0, 1), while the range of the last > > bucket is [pow(hist_param, size-1), +INF). Otherwise the Nth bucket > > (1-indexed) covers [pow(hist_param, N-2), pow(histparam, N-1)). > > > > > + ``size``) is [pow(``hist_param``, N-2), pow(``hist_param``, N-1)). The range > > > + of the first bucket is [0, 1), while the range of the last bucket is > > > + [pow(``hist_param``, ``size``-2), +INF). The bucket value indicates how many > > > + times the statistics data is in the bucket's range. > > > > > > Bits 4-7 of ``flags`` encode the unit: > > > * ``KVM_STATS_UNIT_NONE`` > > > @@ -5246,9 +5267,10 @@ unsigned 64bit data. > > > The ``offset`` field is the offset from the start of Data Block to the start of > > > the corresponding statistics data. > > > > > > -The ``unused`` field is reserved for future support for other types of > > > -statistics data, like log/linear histogram. Its value is always 0 for the types > > > -defined above. > > > +The ``hist_param`` field is used as a parameter for histogram statistics data. > > > +For linear histogram statistics data, it indicates the size of a bucket. For > > > +logarithmic histogram statistics data, it indicates the base of the logarithm. > > > +Only base of 2 is supported fo logarithmic histogram. > > > > s/fo/for/ > > > > > > > > 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 > > > @@ -7182,3 +7204,11 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset > > > of the result of KVM_CHECK_EXTENSION. KVM will forward to userspace > > > the hypercalls whose corresponding bit is in the argument, and return > > > ENOSYS for the others. > > > + > > > +8.35 KVM_CAP_STATS_BINARY_FD > > > +---------------------------- > > > + > > > +:Architectures: all > > > + > > > +This capability indicates the feature that userspace can get a file descriptor > > > +for every VM and VCPU to read statistics data in binary format. > > > -- > > > 2.32.0.93.g670b81a890-goog > > >