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Auflistung nach Autor:in "Ramsauer, Ralf"

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  • Konferenzbeitrag
    The List is the Process: Reliable Pre-Integration Tracking of Commits on Mailing Lists
    (Software Engineering 2020, 2020) Ramsauer, Ralf; Lohmann, Daniel; Mauerer, Wolfgang
    International Conference on Software Engineering 2019, Technical Track. Artifact evaluation: available and evaluated. Code+Data available as reproducible OSS. Research on software evolution often focuses on mining changes in software repositories, but omits their pre-integration history. Our work allows for tracking this invisible evolution of software changes on mailing lists (used by many low-level system components) by connecting all early revisions of changes to their final version in repositories. Since only updates to fragments (i.e., patches) are available, identifying semantically similar changes is a non-trivial task that we solve language-independently. We evaluate our method on high-profile OSS projects like the Linux kernel, and validate its high accuracy using an elaborately created ground truth. Our approach can quantify properties of OSS development processes, which is an essential requirement for using OSS in reliable or safety-critical industrial products. We can also quantitatively determine if an open development process effectively aligns with given formal process requirements. We will report on integration of our results in workflows of the Linux Foundation, one of the largest non-profit technology consortia for open source, and joint work with the automotive industry to deploy our results in practise.
  • Textdokument
    Silentium! Run-Analyse-Eradicate the Noise out of the DB/OS Stack
    (BTW 2021, 2021) Mauerer, Wolfgang; Ramsauer, Ralf; Lucas, Edson; Lohmann, Daniel; Scherzinger, Stefanie
    When multiple tenants compete for resources, database performance tends to suffer. Yet there are several scenarios where guaranteed sub-millisecond latencies are crucial, such as in real-time scenarios, IoT, or when operating in safety-critical environments. In this paper, we study how to make query latencies deterministic in the face of noise (whether caused by other tenants or unrelated operating systems tasks). We perform controlled experiments with an in-memory database in a multi-tenant setting, where we successively eradicate noisy interference from within the system software stack, to the point where the engine runs close to bare-metal on the underlying hardware. We show that we can achieve query latencies comparable to the database engine running as the sole tenant, but without noticeably impacting the workload of competing tenants. We discuss these results in the context of ongoing efforts to build custom operating systems for database workloads, and point out that for certain use cases, the margin for improvement is rather narrow. In fact, for scenarios like ours, existing operating systems might just be good enough, provided that they are expertly configured. We then critically discuss these findings in the light of a broader family of database systems (e.g., including disk-based), and the technological disruption of the advances in modern hardware.