Unconference I track

Friday, September 15, 2017 from 9:30am12:30pm
Platinum H/G/F

LPC Unconference

Proposals for this track

* Automated testing of LKML patches with Clang

It's useful to have bots automatically test proposed patches and notify authors when they fail to compile in certain configurations. Currently for Clang, a few folks interested in supporting it email authors when patches break things, but regression finding is currently not automated for Clang. I'd like to pick some brains as to what is a smart way to automatically test proposed patches for a seemingly limitless number of kernel configurations.
Unconference I 09/15/2017
Nick Desaulniers

* ktask: multithread cpu-intensive kernel work

As memory size and CPU counts increase on the largest systems, certain paths in the kernel that are single-threaded today are not scaling well and will become even bigger bottlenecks in the future. Examples include zeroing the biggest huge pages (e.g. 1G on x86), walking a process’s entire page table, and freeing large ranges of pages. These paths have been well optimized in one thread, so now it's a matter of scaling up the CPUs to match the amount of work to be done. One solution to this problem is ktask, a generic framework built on top of workqueues that takes care of splitting up a large task, starting a number of threads appropriate for the size of the task and the system, and load balancing the work between these threads. ktask uses internal limits to maintain an appropriate level of concurrency across the system. I want to get feedback on the overall approach and discuss similar scalability issues others are having in the kernel.
Unconference I 09/15/2017
James E.J. Bottomley

* Support for adding DT based thermal zones at runtime

During a recent project I encountered an issue where I needed support for thermal zones that get instantiated by a devicetree overlay. In our specific case we had temperature sensors on a daughtercard that is swap-able. I haven't found a good solution on how to make the current of-thermal code work with runtime added thermal-zones, (assumption is all thermal zones present at boot) and was wondering if people have clever ideas.
Unconference I 09/15/2017
James E.J. Bottomley