[PATCH 0/2] perf kvm: Add kvm stat support on riscv

Shenlin Liang
2024-03-28T03:20:34Z

'perf kvm stat report/record' generates a statistical analysis of KVM
events and can be used to analyze guest exit reasons. This patch tries
to add stat support on riscv.

Map the return value of trace_kvm_exit() to the specific cause of the
exception, and export it to userspace.

It records on two available KVM tracepoints for riscv: "kvm:kvm_entry"
and "kvm:kvm_exit", and reports statistical data which includes events
handles time, samples, and so on.

Simple tests go below:

# ./perf kvm record -e "kvm:kvm_entry" -e "kvm:kvm_exit"
Lowering default frequency rate from 4000 to 2500.
Please consider tweaking /proc/sys/kernel/perf_event_max_sample_rate.
[ perf record: Woken up 18 times to write data ]
[ perf record: Captured and wrote 5.433 MB perf.data.guest (62519 samples)

# ./perf kvm report
31K kvm:kvm_entry
31K kvm:kvm_exit

# ./perf kvm stat record -a
[ perf record: Woken up 3 times to write data ]
[ perf record: Captured and wrote 8.502 MB perf.data.guest (99338 samples) ]

# ./perf kvm stat report --event=vmexit
Event name Samples Sample% Time (ns) Time% Max Time (ns) Min Time (ns) Mean Time (ns)
STORE_GUEST_PAGE_FAULT 26968 54.00% 2003031800 40.00% 3361400 27600 74274
LOAD_GUEST_PAGE_FAULT 17645 35.00% 1153338100 23.00% 2513400 30800 65363
VIRTUAL_INST_FAULT 1247 2.00% 340820800 6.00% 1190800 43300 273312
INST_GUEST_PAGE_FAULT 1128 2.00% 340645800 6.00% 2123200 30200 301990
SUPERVISOR_SYSCALL 1019 2.00% 245989900 4.00% 1851500 29300 241403
LOAD_ACCESS 986 1.00% 671556200 13.00% 4180200 100700 681091
INST_ACCESS 655 1.00% 170054800 3.00% 1808300 54600 259625
HYPERVISOR_SYSCALL 21 0.00% 4276400 0.00% 716500 116000 203638

Shenlin Liang (2):
RISCV: KVM: add tracepoints for entry and exit events
perf kvm/riscv: Port perf kvm stat to RISC-V

arch/riscv/kvm/trace_riscv.h | 60 ++++++++++++++
arch/riscv/kvm/vcpu.c | 7 ++
tools/perf/arch/riscv/Makefile | 1 +
tools/perf/arch/riscv/util/Build | 1 +
tools/perf/arch/riscv/util/kvm-stat.c | 78 +++++++++++++++++++
.../arch/riscv/util/riscv_exception_types.h | 41 ++++++++++
6 files changed, 188 insertions(+)
create mode 100644 arch/riscv/kvm/trace_riscv.h
create mode 100644 tools/perf/arch/riscv/util/kvm-stat.c
create mode 100644 tools/perf/arch/riscv/util/riscv_exception_types.h

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2.37.2