Linus Torvalds announced the release of Linux 5.14, which came mere days after the 30th birthday of his very first Linux announcement. The new kernel includes features such as “core scheduling” (a defence against speculation attacks that span multiple threads) and a new io priority “rq-qos” Quality of Service policy that allows I/O bandwidth to be prioritised within different Linux cgroups.
With the release of 5.14 came the opening of the “merge window” for what will become Linux 5.15. Among the many patches pulled thus far is the core real time “preemption” locking code, and support for scheduling on “asymmetric” systems such as those with Arm “big.LITTLE” clusters of “big” (high performance) and “little” (high efficiency) cores where each of those cores doesn’t have uniform architectural capabilities. A classic example comes when some Arm cores don’t support 32-bit, but a similar situation could even arise on x86 with some cores not supporting AVX512 vector operations. Other more complex constraints are likely in future.