Sr. Staff Performance Tuning Engineer - CPU PMU & Virtualization

About NIO NIO Inc. is a pioneer and a leading company in the global smart electric vehicle market. Founded in November 2014, NIO aspires to shape a sustainable and brighter future with the mission of “Blue Sky Coming”. NIO envisions itself as a user enterprise where innovative technology meets experience excellence. NIO designs, develops, manufactures and sells smart electric vehicles, driving innovations in next-generation core technologies. NIO distinguishes itself through continuous technological breakthroughs and innovations, exceptional products and services, and a community for shared growth. NIO provides premium smart electric vehicles under the NIO brand, premium smart electric vehicles for families through the ONVO brand, and small smart high-end electric cars with the FIREFLY brand. Responsibilities Performance Analysis and OptimizationIdentify and analyze performance bottlenecks across CPU, memory hierarchy, cache, interconnect, and interrupt subsystems.Leverage hardware PMU counters to measure and interpret cycles, instructions, cache misses, branch mispredictions, TLB misses, and stall cycles.Compute and analyze performance metrics such as IPC, CPI, MPKI, memory bandwidth utilization, and stall breakdowns.Optimize system software, applications, and drivers for throughput, latency, and performance determinism. Virtualization Performance TuningProfile and reduce hypervisor overhead, including VM exits, interrupt injection, and stage-2 MMU translation costs.Optimize vCPU placement strategies, huge page usage, and IRQ affinity for performance-sensitive workloads.Analyze and tune virtio and IOMMU performance paths.Investigate cross-core and cross-cluster latency issues, including IPI overhead and interrupt routing on ARM-based systems. CPU PMU and Microarchitectural AnalysisConfigure and interpret ARM PMUv3 and related vendor-specific performance monitoring extensions.Apply Top-Down Microarchitecture Analysis (TMA) to identify frontend/backend bottlenecks.Correlate PMU-derived metrics with kernel traces, source code paths, and system behavior.Design and implement custom event sets tailored to workload-specific performance characterization. Required QualificationsBachelor’s, Master’s, or Ph.D. in Computer Science, Electrical Engineering, or a related field.8+ years of experience in system performance engineering or related roles.Strong understanding of computer architecture, including:CPU pipelines, execution engines, and memory hierarchyInterrupt architectures (e.g., GICv3/GICv4, APIC concepts)MMU, virtual memory, and page table structuresDeep expertise with Linux performance tooling:perfeBPF / BCC / bpftraceftrace / trace-cmdProficiency in C/C++, Python, and shell scripting for performance tooling and automation. Preferred QualificationsHands-on experience with ARM PMUv3 on Cortex-A55/A76/A78 or Neoverse platforms.Experience with one or more virtualization stacks:KVM/QEMUXenseL4 or other RTOS/hypervisor environments Benefits: Along with competitive pay, as a full-time NIO employee, you are eligible for the following benefits on the first day you join NIO:Anthem Blue Cross, HSA, and Kaiser HMO medical plans with $0 for Employee Only Coverage.Dental (including orthodontic coverage) and vision plan. Both provide options with a $0 paycheck contribution covering you and your eligible dependents.Company Paid HSA (Health Savings Account) Contribution when enrolled in the High Deductible Anthem Blue Cross medical planHealthcare and Dependent Care Flexible Spending Accounts (FSA)401(k) with Brokerage Link optionCompany paid Basic Life, AD&D, short-term and long-term disability insuranceEmployee Assistance ProgramSick and Vacation time13 Paid Holidays a yearPaid Parental Leave for first 8 weeks at full pay (eligible after 90 days of employment with NIO)Paid Disability Leave for first 6 weeks at full pay (eligible after 90 days of employment with NIO)Voluntary benefits including: Voluntary Life and AD&D options for you, your spouse/domestic partner and dependent child(ren), pet insuranceCommuter benefitsMobile Cell Phone CreditFree lunch and snacksOnsite gymEmployee discounts and perks program