Reorganized process/thread videos.

plan.txt

@@ -393,9 +393,13 @@ design patterns:
 Combinatorics (n choose k)
 Probability
 Dynamic Programming
+Operating Systems (25 videos):
+    - https://www.youtube.com/watch?v=-KWd_eQYLwY&index=2&list=PL-XXv-cvA_iBDyz-ba4yDskqMDY6A1w_c
+    Covers:
         Processes, Threads, Concurrency issues
-    - difference: https://www.quora.com/What-is-the-difference-between-a-process-and-a-thread
+            - difference
-    - threads: https://www.youtube.com/playlist?list=PL5jc9xFGsL8E12so1wlMS0r0hTQoJL74M
+            - threads:
+                https://www.youtube.com/playlist?list=PL5jc9xFGsL8E12so1wlMS0r0hTQoJL74M
                 - stopped here: https://www.youtube.com/watch?v=_N0B5ua7oN8&list=PL5jc9xFGsL8E12so1wlMS0r0hTQoJL74M&index=4
             - locks
             - mutexes
@@ -404,12 +408,11 @@ Processes, Threads, Concurrency issues
             - how they work
             - deadlock
             - livelock
-Operating Systems (25 videos):
+        CPU activity, interrupts, context switching
-    - https://www.youtube.com/watch?v=-KWd_eQYLwY&index=2&list=PL-XXv-cvA_iBDyz-ba4yDskqMDY6A1w_c
-    Covers:
         Modern concurrency constructs with multicore processors
-        Process resource needs
+        Process resource needs (memory: code, static storage, stack, heap, and also file descriptors, i/o)
-        Thread resource needs
+        Thread resource needs (shares above with other threads in same process but each has its own pc, stack counter, registers and stack)
+        Forking is really copy on write (read-only) until the new process writes to memory, then it does a full copy.
         Context switching
             - How context switching is initiated by the operating system and underlying hardware
 Scheduling