Adding a brief note on priorities to the wiki.

Author: Henry Qin

wiki/Main.md

@@ -6,3 +6,4 @@ questions related to both the user and kernel sides of the Arachne system.
 # Current Topics
 
  - [Kernel API & Core Negotiation Protocol](wiki/KernelAPI.md)
+ - [Priorities & Starvation](wiki/Priorities.md)

wiki/Priorities.md

@@ -0,0 +1,15 @@
+# Priorities and Starvation
+
+## Open Questions
+
+ - Are priorities necessary for good performance within an application in
+   addition to between applications?
+ - What is a reasonable policy concerning starvation?
+ - What is the performance cost of having arbitrary priority levels?
+
+## Ideas for preventing starvation
+
+1. Require that the number of CPU-bound high priority threads is lower than the
+   number of cores.
+2. Ensure there is at least one core to run only low priority threads, even if
+   that means putting more than one high-priority thread on the same core.