up

Author: selimslab

_CONTENT/eng/data/dist.md

@@ -49,29 +49,35 @@ rebalancing is expensive
     service discovery, request routing 
 ```
 
-
 ## consistency
 linearizable: single copy illusion, single leader + election consensus + sync replication
+
 causal: vector clocks + dependency tracking
+
 eventual: async replication + conflict resolution
 
 ## consensus
 raft: majority ack, term number fencing 
 
-paxos
-pbft: o(n2)
-
 ## atomic commit
 2PC: ask all, commit if they all ack, like marriage, coordinator spof 
 practical: 2pc + raft for coordinator failover 
-k
+
 ## time and order 
 NTP, GPS 
 
 lamport clock: single counter per process, can only tell if A happens-before B
+
 vector clocks: list of counters per process, can detect concurrency, detects conflicts 
+
 version vector: each replica tracks versions of replicated data objects 
 
+```
+lamport int 
+vector []int 
+versions map[object]version
+```
+
 ## availability
 heartbeat pings with timeout, adapt to network conditions
 lease with ttl

_CONTENT/eng/os/proc.md

@@ -1,26 +1,18 @@
 ---
 ---
-## address space
 ```
-code <- PC program counter or IP instruction pointer
+address space
+    code <- IP or PC
+        instruction pointer or program counter
+    data
+    heap
+        malloc
+    stack <- SP
+        params
+        return address
+        local vars
+        open files
 
-data
-
-stack <- SP
-    return address
-    open files
-    params
-    local vars
-
-heap
-    new()
-    malloc()
-```
-
-time sharing, save/load registers to switch ctx
-scheduler: policy vs mechanism
-
-```
 fork()
 exec()
 wait()
@@ -36,9 +28,7 @@ pthread
     cond
         wait
         signal
-```
 
-```
 IPC
     shared memory
         threads
@@ -53,12 +43,10 @@ signals
     SIGINT
     SIGTERM
     SIGHUP
-```
 
-## virt
-```
-host os, qemu, kvm
-vm, guest os, containerd, runc
-kubelet, kube-proxy, coredns
-pod, container
+virt
+    host os, qemu, kvm
+    vm, guest os, containerd, runc
+    kubelet, kube-proxy, coredns
+    pod, container, process
 ```

_CONTENT/eng/os/system.md

@@ -27,10 +27,7 @@ systemd
     syslogd
     journald
 
-```
 
-## users
-```
 user types
     root
     service accounts