kernel/linux.git/tools/testing/selftests/resctrl/cat_test.c, branch v7.2-rc1

selftests/resctrl: Reduce L2 impact on CAT test

2026-05-05T00:40:02+00:00

The L3 CAT test loads a buffer into cache that is proportional to the L3 size allocated for the workload and measures cache misses when accessing the buffer as a test of L3 occupancy. When loading the buffer it can be assumed that a portion of the buffer will be loaded into the L2 cache and depending on cache design may not be present in L3. It is thus possible for data to not be in L3 but also not trigger an L3 cache miss when accessed. Reduce impact of L2 on the L3 CAT test by, if L2 allocation is supported, minimizing the portion of L2 that the workload can allocate into. This encourages most of buffer to be loaded into L3 and support better comparison between buffer size, cache portion, and cache misses when accessing the buffer. Link: https://lore.kernel.org/r/1f5aad318889cd6d4f9a8d8b0fbe83e3848d41a9.1775266384.git.reinette.chatre@intel.com Signed-off-by: Reinette Chatre Tested-by: Chen Yu Reviewed-by: Ilpo Järvinen Signed-off-by: Shuah Khan

selftests/resctrl: Simplify perf usage in CAT test

2026-05-05T00:40:02+00:00

The CAT test relies on the PERF_COUNT_HW_CACHE_MISSES event to determine if modifying a cache portion size is successful. This event is configured to report the data as part of an event group, but no other events are added to the group. Remove the unnecessary PERF_FORMAT_GROUP format setting. This eliminates the need for struct perf_event_read and results in read() of the associated file descriptor to return just one value associated with the PERF_COUNT_HW_CACHE_MISSES event of interest. Link: https://lore.kernel.org/r/fb69325eba5031b735fa79effaaacd797c9c6040.1775266384.git.reinette.chatre@intel.com Signed-off-by: Reinette Chatre Tested-by: Chen Yu Reviewed-by: Ilpo Järvinen Signed-off-by: Shuah Khan

selftests/resctrl: Remove requirement on cache miss rate

2026-05-05T00:40:02+00:00

As the CAT test reads the same buffer into different sized cache portions it compares the number of cache misses against an expected percentage based on the size of the cache portion. Systems and test conditions vary. The CAT test is a test of resctrl subsystem health and not a test of the hardware architecture so it is not required to place requirements on the size of the difference in cache misses, just that the number of cache misses when reading a buffer increase as the cache portion used for the buffer decreases. Remove additional constraint on how big the difference between cache misses should be as the cache portion size changes. Only test that the cache misses increase as the cache portion size decreases. This remains a good sanity check of resctrl subsystem health while reducing impact of hardware architectural differences and the various conditions under which the test may run. Increase the size difference between cache portions to additionally avoid any consequences resulting from smaller increments. Link: https://lore.kernel.org/r/6de4da5486354c0f25fef0d194956470cb744041.1775266384.git.reinette.chatre@intel.com Signed-off-by: Reinette Chatre Tested-by: Chen Yu Reviewed-by: Ilpo Järvinen Signed-off-by: Shuah Khan

selftests/resctrl: Fix non-contiguous CBM check for Hygon

2026-01-09T23:49:01+00:00

The resctrl selftest currently fails on Hygon CPUs that always supports non-contiguous CBM, printing the error: "# Hardware and kernel differ on non-contiguous CBM support!" This occurs because the arch_supports_noncont_cat() function lacks vendor detection for Hygon CPUs, preventing proper identification of their non-contiguous CBM capability. Fix this by adding Hygon vendor ID detection to arch_supports_noncont_cat(). Link: https://lore.kernel.org/r/20251217030456.3834956-5-shenxiaochen@open-hieco.net Signed-off-by: Xiaochen Shen Reviewed-by: Reinette Chatre Reviewed-by: Fenghua Yu Signed-off-by: Shuah Khan

selftests:resctrl: Fix build failure on archs without __cpuid_count()

2024-09-06T16:46:03+00:00

When resctrl is built on architectures without __cpuid_count() support, build fails. resctrl uses __cpuid_count() defined in kselftest.h. Even though the problem is seen while building resctrl on aarch64, this error can be seen on any platform that doesn't support CPUID. CPUID is a x86/x86-64 feature and code paths with CPUID asm commands will fail to build on all other architectures. All others tests call __cpuid_count() do so from x86/x86_64 code paths when _i386__ or __x86_64__ are defined. resctrl is an exception. Fix the problem by defining __cpuid_count() only when __i386__ or __x86_64__ are defined in kselftest.h and changing resctrl to call __cpuid_count() only when __i386__ or __x86_64__ are defined. In file included from resctrl.h:24, from cat_test.c:11: In function ‘arch_supports_noncont_cat’, inlined from ‘noncont_cat_run_test’ at cat_test.c:326:6: ../kselftest.h:74:9: error: impossible constraint in ‘asm’ 74 | __asm__ __volatile__ ("cpuid\n\t" \ | ^~~~~~~ cat_test.c:304:17: note: in expansion of macro ‘__cpuid_count’ 304 | __cpuid_count(0x10, 1, eax, ebx, ecx, edx); | ^~~~~~~~~~~~~ ../kselftest.h:74:9: error: impossible constraint in ‘asm’ 74 | __asm__ __volatile__ ("cpuid\n\t" \ | ^~~~~~~ cat_test.c:306:17: note: in expansion of macro ‘__cpuid_count’ 306 | __cpuid_count(0x10, 2, eax, ebx, ecx, edx); Fixes: ae638551ab64 ("selftests/resctrl: Add non-contiguous CBMs CAT test") Reported-by: Muhammad Usama Anjum Closes: https://lore.kernel.org/lkml/20240809071059.265914-1-usama.anjum@collabora.com/ Reported-by: Ilpo Järvinen Signed-off-by: Shuah Khan Acked-by: Reinette Chatre Reviewed-by: Muhammad Usama Anjum Reviewed-by: Ilpo Järvinen Signed-off-by: Shuah Khan

selftests/resctrl: Remove test name comparing from write_bm_pid_to_resctrl()

2024-07-11T17:23:54+00:00

write_bm_pid_to_resctrl() uses resctrl_val to check test name which is not a good interface generic resctrl FS functions should provide. Tests define mongrp when needed. Remove the test name check in write_bm_pid_to_resctrl() to only rely on the mongrp parameter being non-NULL. Remove write_bm_pid_to_resctrl() resctrl_val parameter and resctrl_val member from the struct resctrl_val_param that are not used anymore. Similarly, remove the test name constants that are no longer used. Signed-off-by: Ilpo Järvinen Tested-by: Babu Moger Reviewed-by: Reinette Chatre Signed-off-by: Shuah Khan

selftests/resctrl: Fix non-contiguous CBM for AMD

2024-06-26T19:22:34+00:00

The non-contiguous CBM test fails on AMD with: Starting L3_NONCONT_CAT test ... Mounting resctrl to "/sys/fs/resctrl" CPUID output doesn't match 'sparse_masks' file content! not ok 5 L3_NONCONT_CAT: test AMD always supports non-contiguous CBM but does not report it via CPUID. Fix the non-contiguous CBM test to use CPUID to discover non-contiguous CBM support only on Intel. Fixes: ae638551ab64 ("selftests/resctrl: Add non-contiguous CBMs CAT test") Signed-off-by: Babu Moger Reviewed-by: Reinette Chatre Reviewed-by: Ilpo Järvinen Signed-off-by: Shuah Khan

selftests/resctrl: Move cleanups out of individual tests

2024-05-06T19:57:19+00:00

Every test calls its cleanup function at the end of it's test function. After the cleanup function pointer is added to the test framework this can be simplified to executing the callback function at the end of the generic test running function. Make test cleanup functions static and call them from the end of run_single_test() from the resctrl_test's cleanup function pointer. Signed-off-by: Maciej Wieczor-Retman Reviewed-by: Reinette Chatre Signed-off-by: Shuah Khan

selftests/resctrl: Add cleanup function to test framework

2024-05-06T19:57:19+00:00

Resctrl selftests use very similar functions to cleanup after themselves. This creates a lot of code duplication. Also not being hooked to the test framework means that ctrl-c handler isn't aware of what test is currently running and executes all cleanups even though only one is needed. Add a function pointer to the resctrl_test struct and attach to it cleanup functions from individual tests. Signed-off-by: Maciej Wieczor-Retman Reviewed-by: Reinette Chatre Signed-off-by: Shuah Khan

selftests/resctrl: Add non-contiguous CBMs CAT test

2024-02-23T22:19:25+00:00

Add tests for both L2 and L3 CAT to verify the return values generated by writing non-contiguous CBMs don't contradict the reported non-contiguous support information. Use a logical XOR to confirm return value of write_schemata() and non-contiguous CBMs support information match. Signed-off-by: Maciej Wieczor-Retman Reviewed-by: Reinette Chatre Reviewed-by: Ilpo Järvinen Signed-off-by: Shuah Khan