Re: [PATCH v1 2/4] KVM: stats: Update doc for histogram statistics

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Jul 7, 2021 at 6:31 PM David Matlack <dmatlack@xxxxxxxxxx> 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 <jingzhangos@xxxxxxxxxx>
> > ---
> >  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
> >
> >       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``)
> > +    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 <
> > +    ``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.
> >
> >  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.
>
> This should probably be in a separate patch with a Fixes tag.
>
> Fixes: fdc09ddd4064 ("KVM: stats: Add documentation for binary statistics interface")
>
> > --
> > 2.32.0.93.g670b81a890-goog
> >
Thanks David.
Jing



[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux