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author | Karolina Drobnik <karolinadrobnik@gmail.com> | 2022-02-28 17:46:51 +0300 |
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committer | Mike Rapoport <rppt@linux.ibm.com> | 2022-03-10 13:19:44 +0300 |
commit | 58ffc34896db2e5e49e6ae6bf8042f85504d84e8 (patch) | |
tree | eb176379cae19f274f4f4a81c9b8fa21ae1c26b9 /tools | |
parent | 9d8f6abe980f98ffccad80b11d46df2116d7a5fc (diff) | |
download | linux-58ffc34896db2e5e49e6ae6bf8042f85504d84e8.tar.xz |
memblock tests: Add TODO and README files
Add description of the project, its structure and how to run it.
List what is left to implement and what the known issues are.
Signed-off-by: Karolina Drobnik <karolinadrobnik@gmail.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Link: https://lore.kernel.org/r/d5e39b9f7dcef177ebc14282727447bc21e3b38f.1646055639.git.karolinadrobnik@gmail.com
Diffstat (limited to 'tools')
-rw-r--r-- | tools/testing/memblock/README | 107 | ||||
-rw-r--r-- | tools/testing/memblock/TODO | 28 |
2 files changed, 135 insertions, 0 deletions
diff --git a/tools/testing/memblock/README b/tools/testing/memblock/README new file mode 100644 index 000000000000..ca6afcff013a --- /dev/null +++ b/tools/testing/memblock/README @@ -0,0 +1,107 @@ +================== +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 also possible to override different +configuration parameters. For example, to simulate enabled NUMA, use: + +$ make NUMA=1 + +For the full list of 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 diff --git a/tools/testing/memblock/TODO b/tools/testing/memblock/TODO new file mode 100644 index 000000000000..c25b2fdec45e --- /dev/null +++ b/tools/testing/memblock/TODO @@ -0,0 +1,28 @@ +TODO +===== + +1. Add verbose output (e.g., what is being tested and how many tests cases are + passing) + +2. Add flags to Makefile: + + verbosity level + + enable memblock_dbg() messages (i.e. pass "-D CONFIG_DEBUG_MEMORY_INIT" + flag) + +3. Add tests trying to memblock_add() or memblock_reserve() 129th region. + This will trigger memblock_double_array(), make sure it succeeds. + *Important:* These tests require valid memory ranges, use dummy physical + memory block from common.c to implement them. It is also very + likely that the current MEM_SIZE won't be enough for these + test cases. Use realloc to adjust the size accordingly. + +4. Add test cases using this functions (implement them for both directions): + + memblock_alloc_raw() + + memblock_alloc_exact_nid_raw() + + memblock_alloc_try_nid_raw() + +5. Add tests for memblock_alloc_node() to check if the correct NUMA node is set + for the new region + +6. Update comments in tests/basic_api.c to match the style used in + tests/alloc_*.c |