exercise10

Exercise Sheet 10

This week we continue with memory management.

Task 1

Extend your membench application from last week to make its memory allocation behavior a bit more interesting:

• First, perform N allocations of random sizes between S and 8*S. Make sure to use rand_r as your random number generator.
• Then, free some of the allocations you've made. For this, go over your allocations and randomly (with a 50% chance) decide whether to free them or not.
• Allocate another N/2 blocks of random size, as before.
• Finally, free all allocated blocks.

Task 2

Implement a free list allocator (see lecture slides) which uses free lists for requests up to 2^20 Bytes (one separate free list for each power of 2).

As in last week's exercise, create one version that uses a global set of free lists with access locks, and another which uses a separate allocator for each thread.

Task 3

Use the new membench implemented in Task 1 to compare all 4 of your allocators from this week and last week as well as the default system allocator. Perform your comparisons across 1, 2, 4 and 8 threads, and for allocations of S=2^X Bytes for X=4...16.