Refine plan for foundations

plan/20_foundations.md

@@ -1,11 +1,52 @@
-# State of the Art
+# Foundations
 
-En vrac :
+## A dive into processors' microarchitecture
 
-Outils utilisés :
-* Pipedream
-* Valgrind
-* QEmu
+### High-level abstraction
+
+* Highest level of abstraction: instructions -> CPU => modify internal state
+* instructions => ISA, asm
+* state: registers, memory hierarchy, (external effects)
+
+### Microarchitecture
+
+* [big picture figure]
+* Roughly speaking:
+    * frontend (decoder, renamer, other stuff).
+    * backend (execution ports, execution units)
+    * register file
+    * caches
+* Instruction --[frontend]--> Mop, muop
+* muop --[backend port]--> retired [side effects]
+* vast majority of cases: execution units are fully pipelined
+    * Dependencies are breaking the pipeline!
+    * Renamer: helps up to a point
+* out of order CPUs:
+    * Frontend in order up to some point
+    * ROB
+    * backend out-of-order
+    * ROB: execution window. ILP limited to this window.
+
+* Hardware counters
+
+* SIMD
+
+## Prerequisites on code analyzers
+
+* Code analyzers: given a program that is assumed to be the
+  body of a hot loop, derive performance metrics and any information that might
+  help towards performance debugging.
+* Usually static (vs dynamic); focus on static.
+* Very close to the machine: assembly, assembled bytes
+* Examples with llvm-mca
+* Resides in an object or executable file: ELF on Linux and most Unix-based
+  platforms
+* Assembly: straight-line instructions, with (possibly conditional) jumps
+* Instruction identified by its program counter
+* Notion of basic block
+    * Regions of interest: hottest basic blocks
+
+## State of the art
 
 Throughput pred. :
 * Agner Fog
@@ -17,10 +58,7 @@ Throughput pred. :
 * OSACA
 * UiCA
 
-Benchmark suites:
-* Polybench
-* SPEC
-
+## Maybe put this somewhere
 Backend models:
 * To predict the throughput of a kernel, a precise model of the CPU backend is
   required
@@ -29,4 +67,3 @@ Backend models:
     * but this is often incomplete, sometimes even wrong
 * Agner Fog
 * Uops.info
-

plan/to_introduce_early.md

@@ -1,12 +1,10 @@
 # Stuff that must be introduced early (intro/foundations)
 
-* Static vs. dynamic
-* PC
-* ELF
+## Intro to CPUs
+
 * ISA
 * Assembly
 * SIMD
-* Basic block
 * μarch:
     * frontend
     * ports
@@ -18,6 +16,18 @@
     * ROB
     * L1-residence
 * HW counters
+
+## Foundations on code analyzers
+
+* Define Cycles(K): retired instructions
+* Define notion of bottleneck
+* Static vs. dynamic
+* PC
+* ELF
+* Basic block
+
+## State of the art
+
 * Tools:
     * IACA
     * llvm-mca
@@ -25,6 +35,3 @@
     * uops.info
     * UiCA
     * PMEvo
-
-* Define Cycles(K): retired instructions
-* Define notion of bottleneck