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. Signed-off-by: Reinette Chatre <[email protected]> --- tools/testing/selftests/resctrl/cat_test.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c index 6aac03147d41..26062684a9f4 100644 --- a/tools/testing/selftests/resctrl/cat_test.c +++ b/tools/testing/selftests/resctrl/cat_test.c @@ -157,6 +157,12 @@ static int cat_test(const struct resctrl_test *test, if (ret) goto reset_affinity; + if (!strcmp(test->resource, "L3") && resctrl_resource_exists("L2")) { + ret = write_schemata(param->ctrlgrp, "0x1", uparams->cpu, "L2"); + if (ret) + goto reset_affinity; + } + perf_event_attr_initialize(&pea, PERF_COUNT_HW_CACHE_MISSES); pe_fd = perf_open(&pea, bm_pid, uparams->cpu); if (pe_fd < 0) { -- 2.50.1
