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[34.82.80.254]) by smtp.gmail.com with ESMTPSA id e2sm378871pgh.5.2021.07.07.16.31.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jul 2021 16:31:18 -0700 (PDT) Date: Wed, 7 Jul 2021 23:31:14 +0000 From: David Matlack To: Jing Zhang Cc: KVM , KVMPPC , Paolo Bonzini , Sean Christopherson , Jim Mattson , Peter Shier , Oliver Upton , David Rientjes Subject: Re: [PATCH v1 2/4] KVM: stats: Update doc for histogram statistics Message-ID: References: <20210706180350.2838127-1-jingzhangos@google.com> <20210706180350.2838127-3-jingzhangos@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210706180350.2838127-3-jingzhangos@google.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 > > 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 >