Glauber Costa

Costa began his career working on the Linux kernel, with a focus on virtualization and resource isolation. In 2008 he was recognized in the Linux Foundation report "Who Writes Linux" as one of the most active contributors to the Linux Kernel.^[5] In that same year, Linus Torvalds listed him among the top five committers to the x86 subsystem, alongside Ingo Molnár and Thomas Gleixner.^[1] He was also recognized as the third most active 2.6.26 developers (by changeset).^[6]

Costa has done significant work in the development of timekeeping primitives for the KVM hypervisor and developed parts of the memory cgroups subsystem, including early kernel memory accounting features.^[7][8]

In 2011, he implemented the first per-cgroup TCP buffer limits, extending the kernel's memory controller to account for kernel memory such as TCP socket buffers.^[9] He later designed mechanisms to extend memory control groups to additional parts of kernel memory, work that underpinned container isolation in Linux.^[10] Costa also proposed and prototyped cgroup-aware out-of-memory (OOM) handling, allowing policies such as killing all tasks within a memory-constrained cgroup rather than individual processes.^[11]

Costa was a core contributor to Kernel-based Virtual Machine (KVM) and helped merge the KVM codebase into the upstream QEMU emulator.^[12]

In 2013, Costa joined Cloudius Systems, where he co-developed OSv, an open source unikernel targeting cloud workloads.^[13] The OSv design is described in the USENIX ATC 2014 paper "OSv: Optimizing the Operating System for Virtual Machines", a paper that Costa co-authored.^[14]

Costa was part of the team that created ScyllaDB in 2014. He joined as a founding engineer and later advanced to VP of Field Engineering.^[15] He contributed to the engine's open source Seastar framework, shard-per-core architecture, memory and I/O optimizations.^[16]

In 2020, while working at Datadog, Costa developed the Glommio open-source asynchronous Rust programming library. It uses a thread-per-core model and Linux's io_uring to support building highly parallel, low-latency applications on Linux.^[17][18] The project was released publicly by Datadog.^[19]

In 2021, Costa co-founded Turso (initially ChiselStrike) along with Pekka Enberg.^[2][3] The company builds a distributed database that is a reimplementation of SQLite in Rust. Costa serves as the company's CEO.^[4]

Costa has authored technical publications and open-source contributions throughout his career. Notably, he co-authored the research paper "OSv – Optimizing the Operating System for Virtual Machines" presented at USENIX ATC 2014, which detailed the unikernel approach taken by OSv.^[14] Costa has also written technical articles on systems programming (for instance, on how io_uring and eBPF can revolutionize Linux programming).^[20] Additionally, he has spoken at conferences such as USENIX, LinuxCon, KVM Forum, Xen Project Summit, and P99 CONF.^{[21][22][23][24]}