**Overview** Microsoft Advertising is seeking a **Principal Software Engineer** to join our **Ads Engineering Platform** team and advance the core capabilities of our ad-serving infrastructure—the engine that powers advertising across Bing Search, MSN, Microsoft Start, and shopping experiences in the Edge browser. Our serving stack operates at **massive global scale** , delivering **millions of ad requests per second** through a **geo-distributed, low-latency system** that combines **large-scale** **GPU** **/CPU inference, real-time bidding, and intelligent ranking pipelines** . This role focuses on advancing the performance, efficiency, and scalability of the next generation of model serving and inference platforms for Ads.As a senior technical leader, you’ll design and optimize **high-performance serving systems and** **GPU** **inference frameworks** that drive measurable latency improvements and cost efficiency across Microsoft’s ad ecosystem. You’ll work across the stack—from CUDA kernel tuning and NUMA-aware threading to large-scale distributed orchestration and model deployment for deep learning and LLM workloads. This is a rare opportunity to shape the architecture of one of the world’s most advanced, mission-critical online serving platforms, collaborating with world-class engineers to deliver innovation at Internet scale. **Responsibilities** + **Design and lead** the development of large-scale, distributed online serving systems—including GPU-accelerated and CPU-based ranking/inference pipelines—to process millions of ad requests per second with ultra-low latency, high throughput, and strong reliability. + **Architect and optimize** end-to-end inference infrastructure, including model serving, batching/streaming, caching, scheduling, and resource orchestration across heterogeneous hardware (GPU, CPU, and memory tiers). + **Profile and optimize performance** across the full stack—from CUDA kernels and GPU pipelines to CPU threads and OS-level scheduling—identifying bottlenecks, tuning latency tails, and improving cost efficiency through advanced profiling and instrumentation. + **Own live-site reliability** as a DRI: design telemetry, alerting, and fault-tolerance mechanisms; drive rapid diagnosis and mitigation of performance regressions or outages in globally distributed systems. + **Collaborate and mentor** across teams—driving architecture reviews, enforcing engineering excellence, promoting system-level optimization practices, and mentoring others in deep debugging, profiling, and performance engineering. **Qualifications** **Required/minimum qualifications** + Bachelor's Degree in Computer Science or related technical field AND 6+ years technical engineering experience developing high-performance, distributed systems in C++ OR equivalent experience. **Additional or preferred qualifications** + Master's Degree in Computer Science or related technical field AND 8+ years technical engineering experience developing high-performance, distributed systems in C++ OR Bachelor's Degree in Computer Science or related technical field AND 12+ years technical engineering experience developing high-performance, distributed systems in C++ OR equivalent experience. + Industry experience in **advertising or search engine backend systems** , such as large-scale ad ranking, real-time bidding (RTB), or relevance-serving infrastructure. + Hands-on experience with **real-time data streaming systems** (Kafka, Flink, Spark Streaming), **feature-store integration** , and **multi-region deployment** for low-latency, globally distributed services. + Familiarity with **LLM inference optimization** —model sharding, tensor/kv-cache parallelism, paged attention, continuous batching, quantization (AWQ/FP8), and hybrid CPU–GPU orchestration. + Demonstrated success operating large-scale systems with **SLA-based capacity forecasting** , autoscaling, and performance telemetry; proven leadership in cross-functional architecture initiatives and technical mentorship. + Passion for **performance engineering, observability, and deep systems debugging** , with a strong drive to push the limits of serving infrastructure for the next generation of ads and AI models. + **Deep expertise in GPU inference frameworks** such as **NVIDIA Triton Inference Server, CUDA, and TensorRT** , including hands-on experience implementing **custom CUDA kernels** , optimizing memory movement (H2D/D2H), overlapping compute and I/O, and maximizing GPU occupancy and kernel fusion for deep learning and LLM workloads. + **Strong understanding of model-serving trade-offs** —batching vs. streaming, latency vs. throughput, quantization (FP16/BF16/INT8), dynamic batching, continuous model rollout, and adaptive inference scheduling across CPU/GPU tiers. + Proven ability to **profile and optimize GPU and system workloads** —including tensor/memory alignment, compute–memory balancing, embedding table management, parameter servers, hierarchical caching, and vectorized inference for transformer/LLM architectures. + **Expertise in low-level system and OS internals** , including **multi-threading, process scheduling, NUMA-aware memory allocation, lock-free data structures, context switching, I/O stack tuning (NVMe, RDMA), kernel bypass (DPDK, io_uring), and CPU/GPU affinity optimization** for large-scale serving pipelines. Software Engineering IC5 - The typical base pay range for this role across the U.S. is USD $139,900 - $274,800 per year. There is a different range applicable to specific work locations, within the San Francisco Bay area and New York City metropolitan area, and the base pay range for this role in those locations is USD $188,000 - $304,200 per year. Certain roles may be eligible for benefits and other compensation. Find additional benefits and pay information here: https://careers.microsoft.com/us/en/us-corporate-pay This position will be open for a minimum of 5 days, with applications accepted on an ongoing basis until the position is filled. Microsoft is an equal opportunity employer. All qualified applicants will receive consideration for employment without regard to age, ancestry, citizenship, color, family or medical care leave, gender identity or expression, genetic information, immigration status, marital status, medical condition, national origin, physical or mental disability, political affiliation, protected veteran or military status, race, ethnicity, religion, sex (including pregnancy), sexual orientation, or any other characteristic protected by applicable local laws, regulations and ordinances. If you need assistance with religious accommodations and/or a reasonable accommodation due to a disability during the application process, read more about requesting accommodations. (https://careers.microsoft.com/v2/global/en/accessibility.html)