04. Cache

MARS

• «Tools → Data Cache Simulator»
• «Tools → Memory Reference Visualization»

  • 

• Try 2×3=6 examples
  1. Direct Mapping / Fully Associative / 2-Way associative
  2. Cache drop: LRU / Random

Examples:

1. Linear:

      1 .eqv    START   0x10010000
      2 .eqv    SZ      512
      3 .text
      4       li      $t9 0
      5 loop:   lw      $t0 START($t9)
      6       addiu   $t9 $t9 4
      7       blt     $t9 SZ loop
   

2. Gapped

      1 .eqv    START   0x10010000
      2 .eqv    SZ      512
      3 .eqv    HSZ     256
      4 # Direct mapping burns out
      5 # Associative captures
      6 .text
      7       li      $t9 0
      8       li      $t8 HSZ
      9 loop:   lw      $t0 START($t9)
     10       lw      $t1 START($t8)
     11       addiu   $t9 $t9 4
     12       addiu   $t8 $t8 4
     13       blt     $t9 HSZ loop
   

3. Equidistance (try to vary step):

      1 .eqv    START   0x10010000
      2 .eqv    SZ      256
      3 .eqv    GAP     3               # Try 5, 11
      4 .text
      5       li      $t8 0
      6       li      $t7 GAP
      7       sll     $t7 $t7 2
      8 loopg:  sll     $t9 $t8 2
      9 loop:   lw      $t0 START($t9)
     10       addu    $t9 $t9 $t7
     11       blt     $t9 SZ loop
     12       addiu   $t8 $t8 1
     13       blt     $t8 GAP loopg
   

Task: write a program, that:

1. burns out default fully associative cache with 100% misses
2. +does this in cycle (if previously not)
3. +fills only 256 bytes of memory without a gap

H/W

(can be done in class if time allows)

1. Write a program that utilizes memory sparsely, so it's footprint 100% misses 2-way associative MARS cache simulator, but (almost) fits into 4-way associative cache with 16 lines (blocks) of cache

2. Make it available at sugon server in the subdirectory asm:

      1 localhost$ ssh sugon -p 2131
      2      ...
      3 [your_login@sugon ~]$ mkdir src
      4 [your_login@sugon ~]$ ls -a src
      5 .  ..
      6 [your_login@sugon ~]$ exit
      7      ...
      8 localhost$ scp -P 2131 progCache.asm your_login@sugon:src/
      9 progCache.asm              100%  285    26.7KB/s   00:00
     10 localhost$ ssh sugon -p 2131
     11      ...
     12 [your_login@sugon ~]$ mkdir src
     13 [your_login@sugon ~]$ ls -a src
     14 .  .. progCache.asm
     15