Maintaining A Stable Real-time Kernel Patchset
josephtsalisbury@gmail.com
jsalisbury@kernel.org
Abstract:
The Real Time Linux collaborative project coordinates the maintenance and hosts the repositories for the PREEMPT_RT patchset[0]. This patchset provides the logic for changing a generic vanilla kernel into a real-time operating system.
The real-time patchset is developed in...
Program verification, ie, producing a proof that code matches its specification, can be seen as the ultimate form of bug finding. Nevertheless, program verification is widely considered to be difficult and time consuming. Furthermore, in the case of the Linux kernel, any verification effort is likely quickly out of date, given the rate of change in the code base. Still, it is not necessarily...
Data Placement has been one of major the sources of innovation in storage. Specifically in NAND Memory, technologies such as Open-Channel SSDs, Key-Value SSDs, Multi Stream, Zoned Namespaces (ZNS), and lately Flexible Data Placement (FDP) have attempted at covering different use-cases. While there is overlap among several of these technologies, they exhibit significant differences when it...
The email workflow brought the kernel to life, saw it through immense growth, and into widespread popularity. However, it seems to be reaching its limits, prompting Linus to say we need to "find ways to get away from the email patch model" to make maintainer life easier.
Kernel workflow evolution (1991 - start, 2002 - BitKeeper, 2005 - Git, 2008 - Patchwork) seems to have stopped fifteen...
Reference counting in Linux kernel is often implemented using
conditional atomic increment/decrement operations on a counter. These
atomic operations can become a scalability bottleneck with increasing
numbers of CPUs. The RCURef patch series [1] and Nginx refcount
scalability issues [2] are recent examples where the refcount bottleneck
significantly degraded application...
The introduction of the new -Wflex-array-member-not-at-end compiler option, released in GCC-14, has revealed approximately 60,000 warnings in the Linux kernel. Among them, some legitimate bugs have been uncovered.
In this presentation, we will explore in detail the different strategies we are employing to resolve all these warnings. These methods have already helped us resolve about 30% of...
Modified condition/decision coverage (MC/DC) is a fine-grained code coverage
metric required by many safety-critical industrial standards, including
aerospace, automotive, medical and rail. It is challenging to measure MC/DC of
targets as complex as Linux kernel. We will discuss our effort on measuring
MC/DC of Linux and the opportunities it would open up. The main challenges...
KernelCI started 10 years ago as a small project to test the kernel on Arm devices. The project grew over the years and today a new architecture is in place. In this talk, Don and Gustavo will present you the new KernelCI. The KernelCI community put a lot of effort recently to design and implement its new testing architecture with a focus on facilitating the kernel community and industry...
Duplicated symbol names in kallsyms pose challenges for tracing and probing operations in the Linux kernel environment, complicating system observability and debugging.
To tackle this issue, kas_alias is introduced, a new tool added to the kernel build process to identify duplicated symbols and add aliases to them, ensuring existing workflows remain unaltered.
kas_alias operates on...
Some kernel mitigations are very expensive, some others fail to adequately address classes of vulnerabilities. At the same time it is hard for users to make informed cost/benefit decisions about whether to enable a particular mitigation or not.
This presentation critically assesses a handful of past and upcoming security mitigations, proposing a data-driven evaluation of their impact on...
I would like to propose a BoF in honor of Daniel Bristot de Oliveira. I'd like it to be held on Thursday night after the last session, so that all can attend. I may even look to see if it is possible to serve refreshments (beer and wine), that would be paid for by those willing to donate. People would be able to come up and give stories about their memories of Daniel. The purpose of this BoF...
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Double scheduling is a concern with virtualization hosts where the host schedules vcpus without knowing whats run by the vcpu and guest schedules tasks without knowing where the vcpu is physically running. This causes issues related to latencies, power consumption, resource utilization
etc. An ideal solution would be to have a cooperative scheduling framework where the guest and host shares...
The Linux kernel has supported multi-sized THP since v6.8 allowing the use of intermediate sized huge pages less than 2M. ARM64 supports contiguous PTEs where multiple PTE entries can be coalesced one TLB entry. This will increase the size of memory covered by the TLB entries and avoid page table walks to create TLB entries.
We ran a series of benchmarks on Ampere Altra using some popular...