OS/161 Reference Manual


sbrktest - program for testing sbrk


/testbin/sbrktest [test-number ...]


sbrktest contains a number of tests for memory allocation, using the sbrk low-level interface directly instead of via malloc. It is similar to malloctest in general layout and approach, but concentrates on kernel-level memory allocation rather than the behavior of C malloc.

There are 21 tests:
1 Allocate one page.
2 Allocate and free one page.
3 Allocate and free several pages.
4 Allocate several pages and free them one at a time.
5 Check the heap end. This test crashes intentionally.
6 Allocate and check the heap end. This test crashes intentionally.
7 Allocate and free and check the heap end. This test crashes intentionally.
8 Allocate several, free some, then check the heap end. This test crashes intentionally.
9 Allocate all memory in a big chunk.
10 Allocate all memory one page at a time.
11 Allocate a lot and intentionally leak it.
12 Fork and then allocate.
13 Allocate and then fork.
14 Allocate and then fork and free.
15 Allocate, fork, allocate more, and free.
16 Small stress test.
17 Randomized small stress test.
18 Small stress test with specific seed.
19 Large stress test.
20 Randomized large stress test.
21 Large stress test with specific seed.

One or more tests may be run specifically by giving the numbers on the command line; otherwise, sbrktest prints the list and prompts for a test number to run.

Note that the tests that crash intentionally should crash the sbrktest program with an illegal memory access ( SIGSEGV) -- they should not crash your kernel.

The tests that attempt to allocate all available memory may be slow, depending on the per-process limits you place on memory allocation (if any) relative to the amount of available physical RAM.


sbrktest uses the following system calls:

sbrktest should work properly once you have implemented the sbrk system call and a virtual memory system that supports dynamic memory allocation. It will not work with dumbvm.