Merge pull request #4310 from egernst/core-sched

shim: add support for core scheduling

docs/design/README.md

@@ -12,7 +12,7 @@ Kata Containers design documents:
 - [Metrics(Kata 2.0)](kata-2-0-metrics.md)
 - [Design for Kata Containers `Lazyload` ability with `nydus`](kata-nydus-design.md)
 - [Design for direct-assigned volume](direct-blk-device-assignment.md)
-
+- [Design for core-scheduling](core-scheduling.md)
 ---
 
 - [Design proposals](proposals)

docs/design/core-scheduling.md

@@ -0,0 +1,12 @@
+# Core scheduling
+
+Core scheduling is a Linux kernel feature that allows only trusted tasks to run concurrently on
+CPUs sharing compute resources (for example, hyper-threads on a core).
+
+Containerd versions >= 1.6.4 leverage this to treat all of the processes associated with a
+given pod or container to be a single group of trusted tasks. To indicate this should be carried
+out, containerd sets the `SCHED_CORE` environment variable for each shim it spawns. When this is
+set, the Kata Containers shim implementation uses the `prctl` syscall to create a new core scheduling
+domain for the shim process itself as well as future VMM processes it will start.
+
+For more details on the core scheduling feature, see the [Linux documentation](https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/core-scheduling.html).