Linux Plumbers Conference 2022

Session

Real-time and Scheduling MC

13 Sept 2022, 15:00

"Ulster & Munster" (Clayton Hotel on Burlington Road)

48. rtla: what is next?

Daniel Bristot de Oliveira (Red Hat, Inc.)

13/09/2022, 15:00

Presented last year, RTLA made its way to the kernel set of tools.

RTLA includes an interface for timerlat and osnoise tracers in the current state. However, the idea is to expand RTLA to include a vast set of ... real-time Linux analysis tools, combining tracing and methods to stimulate the system.

In this discussion, we can talk about ways to extend tracers and rtla, including:

-...

128. Bringing Energy-Aware Scheduling to x86

Len Brown (Intel Open Source Technology Center), Ricardo Neri (Intel Corporation)

13/09/2022, 15:30

Energy-Aware Scheduling (EAS) is not a straight fit for x86 hybrid processors. Thus, x86 hybrid processors do not make use of EAS yet. A large range of turbo frequencies, inter-CPU dependencies, simultaneous multithreading, and instruction-specific differences in throughput makes it difficult to feed the scheduler with a simple, timely, accurate model of CPU capacity.
Dependencies between...

106. Latency hints for CFS task

Vincent Guittot (Linaro)

13/09/2022, 15:55

RT schedulers are traditionally used for everything concerned with the latency but it's sometimes not possible to use RT for all parts of the system because of the variance of the runtime or the trust of some parts as an example. At the opposite side, some apps don't care at all about latency and preempting the running task but prefer to let the current task move forward.
The latency nice...

65. Linux Kernel Scheduling and split-LLC architectures: Overview, Challenges and Opportunities

Gautham R Shenoy (AMD Inc.), Prateek Nayak (AMD Inc. )

13/09/2022, 16:45

Linux Task Scheduler has seen several enhancements to make task scheduling better and smarter for split last level cache (split-LLC) environments. With wider adoption of the chiplet-like technology in current and future processors, these continued efforts become key to squeeze the most out of the silicon.

Work has already gone in to accurately model the domain topology for split-LLC...

61. Limit the idle CPU search depth and use CPU filter during task wake up

Chen Yu, Yun Wu (Bytedance)

13/09/2022, 17:10

When a task is woken up in the last level cache (LLC) domain, the scheduler tries to find an idle CPU for the task. But when the LLC domain is fully busy, the search for an idle CPU may be in vain, adding long latency to the task wakeup and yet does not lead to an idle CPU. The latency gets worse when the number of CPUs in the LLC increases, which will be the case for future platforms.
During...

135. Linux needs a Scheduler QOS API -- and it isn't nice(2)

Len Brown (Intel Open Source Technology Center)

13/09/2022, 17:35

Optimal task placement decisions and hardware operating points impact application performance and energy efficiency.

The Linux scheduler and the hardware export low level knobs that allow an expert to influence these settings. But that expert needs to know details about the hardware, about the Linux scheduler, and about every (other) task that is running on the system.

This is not a...

255. PREEMPT_RT Q&A with tglx

Thomas Gleixner

13/09/2022, 18:00

In this topic, Thomas Gleixner will answer all the questions about the present of future of the PREEMPT_RT, mainly about the status of the merge and how things will work after the merge.