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![]() This test is aimed at verifying the memblock_alloc_node() to work as expected, so setting the correct NUMA node for the new allocated region. The memblock_alloc_node() is called directly without using any stub. The core check is between the requested NUMA node and the `nid` field inside the memblock_region structure. These two are supposed to be equal for the test to succeed. Signed-off-by: Claudio Migliorelli <claudio.migliorelli@mail.polimi.it> Link: https://lore.kernel.org/r/ea5e938e-6b74-b188-af59-4b94b18bc0@mail.polimi.it Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org> |
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asm | ||
lib | ||
linux | ||
scripts | ||
tests | ||
.gitignore | ||
internal.h | ||
main.c | ||
Makefile | ||
mmzone.c | ||
README | ||
TODO |
================== Memblock simulator ================== Introduction ============ Memblock is a boot time memory allocator[1] that manages memory regions before the actual memory management is initialized. Its APIs allow to register physical memory regions, mark them as available or reserved, allocate a block of memory within the requested range and/or in specific NUMA node, and many more. Because it is used so early in the booting process, testing and debugging it is difficult. This test suite, usually referred as memblock simulator, is an attempt at testing the memblock mechanism. It runs one monolithic test that consist of a series of checks that exercise both the basic operations and allocation functionalities of memblock. The main data structure of the boot time memory allocator is initialized at the build time, so the checks here reuse its instance throughout the duration of the test. To ensure that tests don't affect each other, region arrays are reset in between. As this project uses the actual memblock code and has to run in user space, some of the kernel definitions were stubbed by the initial commit that introduced memblock simulator (commit 16802e55dea9 ("memblock tests: Add skeleton of the memblock simulator")) and a few preparation commits just before it. Most of them don't match the kernel implementation, so one should consult them first before making any significant changes to the project. Usage ===== To run the tests, build the main target and run it: $ make && ./main A successful run produces no output. It is possible to control the behavior by passing options from command line. For example, to include verbose output, append the `-v` options when you run the tests: $ ./main -v This will print information about which functions are being tested and the number of test cases that passed. For the full list of options from command line, see `./main --help`. It is also possible to override different configuration parameters to change the test functions. For example, to simulate enabled NUMA, use: $ make NUMA=1 For the full list of build options, see `make help`. Project structure ================= The project has one target, main, which calls a group of checks for basic and allocation functions. Tests for each group are defined in dedicated files, as it can be seen here: memblock |-- asm ------------------, |-- lib |-- implement function and struct stubs |-- linux ------------------' |-- scripts | |-- Makefile.include -- handles `make` parameters |-- tests | |-- alloc_api.(c|h) -- memblock_alloc tests | |-- alloc_helpers_api.(c|h) -- memblock_alloc_from tests | |-- alloc_nid_api.(c|h) -- memblock_alloc_try_nid tests | |-- basic_api.(c|h) -- memblock_add/memblock_reserve/... tests | |-- common.(c|h) -- helper functions for resetting memblock; |-- main.c --------------. dummy physical memory definition |-- Makefile `- test runner |-- README |-- TODO |-- .gitignore Simulating physical memory ========================== Some allocation functions clear the memory in the process, so it is required for memblock to track valid memory ranges. To achieve this, the test suite registers with memblock memory stored by test_memory struct. It is a small wrapper that points to a block of memory allocated via malloc. For each group of allocation tests, dummy physical memory is allocated, added to memblock, and then released at the end of the test run. The structure of a test runner checking allocation functions is as follows: int memblock_alloc_foo_checks(void) { reset_memblock_attributes(); /* data structure reset */ dummy_physical_memory_init(); /* allocate and register memory */ (...allocation checks...) dummy_physical_memory_cleanup(); /* free the memory */ } There's no need to explicitly free the dummy memory from memblock via memblock_free() call. The entry will be erased by reset_memblock_regions(), called at the beginning of each test. Known issues ============ 1. Requesting a specific NUMA node via memblock_alloc_node() does not work as intended. Once the fix is in place, tests for this function can be added. 2. Tests for memblock_alloc_low() can't be easily implemented. The function uses ARCH_LOW_ADDRESS_LIMIT marco, which can't be changed to point at the low memory of the memory_block. References ========== 1. Boot time memory management documentation page: https://www.kernel.org/doc/html/latest/core-api/boot-time-mm.html