content updates, various fixes

site/content/digests/ATC-2025/index.md

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+---
+title: ATC 2025 Digest
+venue: ATC
+year: 2025
+date: '2025-07-09'
+tags:
+- operating-systems
+- cloud
+- storage
+- networking
+paper_count: 13
+draft: false
+---
+
+13 papers selected.
+
+---
+
+### ASTERINAS: A Linux ABI-Compatible, Rust-Based Framekernel OS with a Small and Sound TCB
+
+*Yuke Peng, Hongliang Tian, Junyang Zhang, Ruihan Li *et al.**
+
+**TL;DR** — A production-grade OS kernel written in Rust that exposes a full Linux ABI while confining unsafe code to a small, formally-audited framekernel core.
+
+**Why notable** — ASTERINAS demonstrates that Linux compatibility and memory-safety guarantees are not mutually exclusive — unsafe Rust is isolated to under 5 kloc of framework code, giving systems operators a credible path toward a safer Linux-compatible kernel without sacrificing application portability.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/peng-yuke)
+
+---
+
+### Rex: Closing the language-verifier gap with safe and usable kernel extensions
+
+*Jinghao Jia, Ruowen Qin, Milo Craun, Egor Lukiyanov *et al.**
+
+**TL;DR** — Rex introduces a new kernel-extension framework that replaces eBPF's in-kernel verifier with a Rust-typed, LLVM-based toolchain to safely express programs that eBPF currently rejects.
+
+**Why notable** — The eBPF verifier's conservatism silently limits what practitioners can implement; Rex shows how a language-level safety guarantee can replace ad-hoc bytecode verification without changing the kernel ABI, opening the door to far richer kernel extensions.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/jia)
+
+---
+
+### PageFlex: Flexible and Efficient User-space Delegation of Linux Paging Policies with eBPF
+
+*Anil Yelam, Kan Wu, Zhiyuan Guo, Suli Yang *et al.**
+
+**TL;DR** — PageFlex lets applications plug in custom page-replacement and allocation policies via eBPF hooks without modifying the kernel, achieving performance competitive with kernel-native policies.
+
+**Why notable** — Memory management policy has historically been locked inside the kernel; PageFlex's eBPF delegation mechanism gives cloud operators a principled way to tailor paging behavior per workload, directly addressing the one-size-fits-all limitation of the Linux page allocator.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/yelam)
+
+---
+
+### μEFI: A Microkernel-Style UEFI with Isolation and Transparency
+
+*Le Chen, Yiyang Wu, Jinyu Gu 0001, Yubin Xia *et al.**
+
+**TL;DR** — μEFI restructures UEFI firmware around microkernel principles so that individual UEFI drivers are isolated from each other and from the boot-time trusted computing base.
+
+**Why notable** — Firmware vulnerabilities are notoriously hard to patch and can persist through OS reinstalls; μEFI's approach substantially reduces the blast radius of a compromised UEFI driver while remaining compatible with existing UEFI software, making it directly relevant to secure-boot infrastructure.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/chen-le)
+
+---
+
+### Z-LFS: A Zoned Namespace-tailored Log-structured File System for Commodity Small-zone ZNS SSDs
+
+*Inhwi Hwang, Sangjin Lee 0003, Sunggon Kim, Hyeonsang Eom *et al.**
+
+**TL;DR** — Z-LFS is an LFS designed around the tight zone-size constraints of commodity ZNS SSDs, using fine-grained segment management and zone-aware garbage collection to avoid the capacity and write-amplification pitfalls of existing approaches.
+
+**Why notable** — ZNS SSDs offer significant cost and endurance advantages but mainstream file systems waste capacity on small-zone devices; Z-LFS shows that rethinking LFS segment layout specifically for small zones yields competitive throughput with substantially lower write amplification.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/hwang)
+
+---
+
+### Crash Consistency in Block-Level Caching Systems: An Open CAS Case Study
+
+*Shaohua Duan, Youmin Chen*
+
+**TL;DR** — A systematic study of crash-consistency bugs in the widely deployed Open CAS block-layer cache, revealing a class of ordering violations that can silently corrupt data on unexpected power loss.
+
+**Why notable** — Block-level caches are invisible to file systems and often assumed to be transparent, making these bugs particularly insidious; the paper's taxonomy and detection methodology are directly actionable for operators running NVMe caching in production storage stacks.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/duan-shaohua)
+
+---
+
+### HotRAP: Hot Record Retention and Promotion for LSM-trees with Tiered Storage
+
+*Jiansheng Qiu, Fangzhou Yuan, Mingyu Gao 0001, Huanchen Zhang*
+
+**TL;DR** — HotRAP adds a retention-and-promotion layer to LSM-tree compaction that keeps frequently accessed records in faster storage tiers by tracking access heat across compaction boundaries.
+
+**Why notable** — Tiered storage deployments with LSM engines (RocksDB, LevelDB) routinely see hot data demoted to slow tiers during compaction; HotRAP's lightweight heat tracking improves read latency by up to 5x on skewed workloads without changing the external LSM API.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/qiu)
+
+---
+
+### TGW: Operating an Efficient and Resilient Cloud Gateway at Scale
+
+*Yifan Yang 0009, Lin He 0004, Jiasheng Zhou, Xiaoyi Shi *et al.**
+
+**TL;DR** — TGW describes the architecture, traffic engineering, and operational lessons of a production cloud gateway handling hundreds of Tbps at a major cloud provider.
+
+**Why notable** — Production-scale gateway papers with real traffic data are rare; TGW's account of how to sustain sub-millisecond failover and linear-scale throughput under adversarial traffic patterns provides a concrete reference design for anyone building or operating large-scale edge infrastructure.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/yang-yifan)
+
+---
+
+### SwCC: Software-Programmable and Per-Packet Congestion Control in RDMA Engine
+
+*Hongjing Huang, Jie Zhang 0081, Xuzheng Chen, Ziyu Song *et al.**
+
+**TL;DR** — SwCC embeds a programmable per-packet congestion-control engine directly inside an RDMA NIC, allowing operators to deploy and hot-swap CC algorithms without CPU involvement or ASIC redesign.
+
+**Why notable** — RDMA congestion control has historically been frozen in NIC firmware, forcing cluster-wide firmware upgrades to try new algorithms; SwCC's programmable datapath brings the velocity of software-defined networking to the RDMA layer at near-line-rate performance.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/huang-hongjing)
+
+---
+
+### Opening Up Kernel-Bypass TCP Stacks
+
+*Shinichi Awamoto, Michio Honda*
+
+**TL;DR** — A framework that exposes kernel-bypass TCP (DPDK-based) stacks to unmodified POSIX applications by transparently interposing at the syscall level, without requiring application changes or root privileges.
+
+**Why notable** — Kernel-bypass networking has been limited to purpose-built applications; this work's zero-modification deployment model makes microsecond-latency TCP accessible to the broad ecosystem of existing networked software, which has significant practical implications for latency-sensitive cloud services.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/awamoto)
+
+---
+
+### Accelerating Nested Virtualization with HyperTurtle
+
+*Ori Ben Zur, Jakob Krebs, Shai Aviram Bergman, Mark Silberstein*
+
+**TL;DR** — HyperTurtle reduces the performance penalty of nested virtualization by selectively forwarding L2 guest hypercalls directly to the L0 hypervisor, bypassing the L1 intermediary for common fast paths.
+
+**Why notable** — Nested virtualization is increasingly important for confidential computing and cloud-in-cloud deployments, but the overhead is often prohibitive; HyperTurtle's selective bypass approach cuts nested VM overhead by up to 60% on I/O-intensive workloads with no guest modifications.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/zur)
+
+---
+
+### KVCache Cache in the Wild: Characterizing and Optimizing KVCache Cache at a Large Cloud Provider
+
+*Jiahao Wang, Jinbo Han, Xingda Wei, Sijie Shen *et al.**
+
+**TL;DR** — A production measurement study of LLM KV-cache behavior across a large cloud fleet, revealing access patterns and reuse characteristics that inform a redesigned caching policy reducing GPU memory pressure significantly.
+
+**Why notable** — As LLM serving becomes a dominant cloud workload, KV-cache management is a critical bottleneck; this paper provides the first at-scale empirical characterization of KV-cache reuse in a real deployment, and its findings directly shaped policy changes that improved cache hit rates by over 30%.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/wang-jiahao)
+
+---
+
+### GREYHOUND: Hunting Fail-Slows in Hybrid-Parallel Training at Scale
+
+*Tianyuan Wu, Wei Wang 0030, Yinghao Yu, Siran Yang *et al.**
+
+**TL;DR** — GREYHOUND is a runtime monitoring system that automatically detects and isolates fail-slow stragglers in large-scale hybrid-parallel LLM training jobs before they degrade the entire training run.
+
+**Why notable** — Fail-slow faults are notoriously harder to detect than fail-stop failures and can silently extend training jobs by hours; GREYHOUND's production deployment demonstrates that fine-grained per-layer timing signals can catch slow nodes within seconds, making it a practical reliability tool for anyone running large training clusters.
+
+[→ Read paper](https://www.usenix.org/conference/atc25/presentation/wu-tianyuan)
+