Re: [PATCH v4 0/4] KVM statistics data fd-based binary interface

Paolo Bonzini
2021-05-11T08:38:58Z

On 10/05/21 20:57, Jing Zhang wrote:
> Hi Paolo,
>
> On Thu, Apr 29, 2021 at 3:37 PM Jing Zhang <jingzhangos@google.com> wrote:
>>
>> This patchset provides a file descriptor for every VM and VCPU to read
>> KVM statistics data in binary format.
>> It is meant to provide a lightweight, flexible, scalable and efficient
>> lock-free solution for user space telemetry applications to pull the
>> statistics data periodically for large scale systems. The pulling
>> frequency could be as high as a few times per second.
>> In this patchset, every statistics data are treated to have some
>> attributes as below:
>> * architecture dependent or common
>> * VM statistics data or VCPU statistics data
>> * type: cumulative, instantaneous,
>> * unit: none for simple counter, nanosecond, microsecond,
>> millisecond, second, Byte, KiByte, MiByte, GiByte. Clock Cycles
>> Since no lock/synchronization is used, the consistency between all
>> the statistics data is not guaranteed. That means not all statistics
>> data are read out at the exact same time, since the statistics date
>> are still being updated by KVM subsystems while they are read out.
>>
>> ---
>>
>> * v3 -> v4
>> - Rebase to kvm/queue, commit 9f242010c3b4 ("KVM: avoid "deadlock"
>> between install_new_memslots and MMU notifier")
>> - Use C-stype comments in the whole patch
>> - Fix wrong count for x86 VCPU stats descriptors
>> - Fix KVM stats data size counting and validity check in selftest
>>
>> * v2 -> v3
>> - Rebase to kvm/queue, commit edf408f5257b ("KVM: avoid "deadlock"
>> between install_new_memslots and MMU notifier")
>> - Resolve some nitpicks about format
>>
>> * v1 -> v2
>> - Use ARRAY_SIZE to count the number of stats descriptors
>> - Fix missing `size` field initialization in macro STATS_DESC
>>
>> [1] https://lore.kernel.org/kvm/20210402224359.2297157-1-jingzhangos@google.com
>> [2] https://lore.kernel.org/kvm/20210415151741.1607806-1-jingzhangos@google.com
>> [3] https://lore.kernel.org/kvm/20210423181727.596466-1-jingzhangos@google.com
>>
>> ---
>>
>> Jing Zhang (4):
>> KVM: stats: Separate common stats from architecture specific ones
>> KVM: stats: Add fd-based API to read binary stats data
>> KVM: stats: Add documentation for statistics data binary interface
>> KVM: selftests: Add selftest for KVM statistics data binary interface
>>
>> Documentation/virt/kvm/api.rst | 171 ++++++++
>> arch/arm64/include/asm/kvm_host.h | 9 +-
>> arch/arm64/kvm/guest.c | 42 +-
>> arch/mips/include/asm/kvm_host.h | 9 +-
>> arch/mips/kvm/mips.c | 67 ++-
>> arch/powerpc/include/asm/kvm_host.h | 9 +-
>> arch/powerpc/kvm/book3s.c | 68 +++-
>> arch/powerpc/kvm/book3s_hv.c | 12 +-
>> arch/powerpc/kvm/book3s_pr.c | 2 +-
>> arch/powerpc/kvm/book3s_pr_papr.c | 2 +-
>> arch/powerpc/kvm/booke.c | 63 ++-
>> arch/s390/include/asm/kvm_host.h | 9 +-
>> arch/s390/kvm/kvm-s390.c | 133 +++++-
>> arch/x86/include/asm/kvm_host.h | 9 +-
>> arch/x86/kvm/x86.c | 71 +++-
>> include/linux/kvm_host.h | 132 +++++-
>> include/linux/kvm_types.h | 12 +
>> include/uapi/linux/kvm.h | 50 +++
>> tools/testing/selftests/kvm/.gitignore | 1 +
>> tools/testing/selftests/kvm/Makefile | 3 +
>> .../testing/selftests/kvm/include/kvm_util.h | 3 +
>> .../selftests/kvm/kvm_bin_form_stats.c | 380 ++++++++++++++++++
>> tools/testing/selftests/kvm/lib/kvm_util.c | 11 +
>> virt/kvm/kvm_main.c | 237 ++++++++++-
>> 24 files changed, 1415 insertions(+), 90 deletions(-)
>> create mode 100644 tools/testing/selftests/kvm/kvm_bin_form_stats.c
>>
>>
>> base-commit: 9f242010c3b46e63bc62f08fff42cef992d3801b
>> --
>> 2.31.1.527.g47e6f16901-goog
>>
>
> Do I need to send another version for this?

No, the merge window has just finished and I wanted to flush the dozens
of bugfix patches that I had. I'll get to it shortly.

Paolo