On Thu, 9 Nov 2023, Maciej Wieczor-Retman wrote:
Non-contiguous CBM support for Intel CAT has been merged into the kernel with Commit 0e3cd31f6e90 ("x86/resctrl: Enable non-contiguous CBMs in Intel CAT") but there is no selftest that would validate if this feature works correctly.
The selftest needs to verify if writing non-contiguous CBMs to the schemata file behaves as expected in comparison to the information about non-contiguous CBMs support.
Add tests for both L2 and L3 CAT to verify if the return values generated by writing non-contiguous CBMs don't contradict the reported non-contiguous support information.
"if ... don't" sounds weird to me. Perhaps the "if" could just be dropped from it.
Comparing the return value of write_schemata() with non-contiguous CBMs support information can be simplified as a logical XOR operation. In other words if non-contiguous CBMs are supported and if non-contiguous write succeeds the test should succeed and if the write fails the test should also fail. The opposite should happen if non-contiguous CBMs are not supported.
To me this sounds a bit verbose given how basic thing it talks about (but maybe I'm too old already to have actually come across a few xor tricks in the past :-)). I'd simplify it to (or simply drop it):
Use a logical XOR to confirm return value of write_schemata() and non-contiguous CBMs support information match.
Signed-off-by: Maciej Wieczor-Retman maciej.wieczor-retman@intel.com
This patch is based on a rework of resctrl selftests that's currently in review [1]. The patch also implements a similiar functionality presented in the bash script included in the cover letter to the original non-contiguous CBMs in Intel CAT series [2].
[1] https://lore.kernel.org/all/20231024092634.7122-1-ilpo.jarvinen@linux.intel.... [2] https://lore.kernel.org/all/cover.1696934091.git.maciej.wieczor-retman@intel...
tools/testing/selftests/resctrl/cat_test.c | 97 +++++++++++++++++++ tools/testing/selftests/resctrl/resctrl.h | 2 + .../testing/selftests/resctrl/resctrl_tests.c | 2 + 3 files changed, 101 insertions(+)
diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c index bc88eb891f35..6a01a5da30b4 100644 --- a/tools/testing/selftests/resctrl/cat_test.c +++ b/tools/testing/selftests/resctrl/cat_test.c @@ -342,6 +342,87 @@ static int cat_run_test(const struct resctrl_test *test, const struct user_param return ret; } +static int noncont_cat_run_test(const struct resctrl_test *test,
const struct user_params *uparams)+{
- unsigned long full_cache_mask, cont_mask, noncont_mask;
- unsigned int eax, ebx, ecx, edx, ret, sparse_masks;
- char res_path[PATH_MAX];
- char schemata[64];
- int bit_center;
- FILE *fp;
- /* Check to compare sparse_masks content to cpuid output. */
- snprintf(res_path, sizeof(res_path), "%s/%s/%s", INFO_PATH,
test->resource, "sparse_masks");- fp = fopen(res_path, "r");
- if (!fp) {
perror("# Error in opening file\n");return errno;- }
- if (fscanf(fp, "%u", &sparse_masks) <= 0) {
perror("Could not get sparse_masks contents\n");fclose(fp);return -1;- }
- fclose(fp);
Add a function to do this conversion into resctrlfs.c.
- if (!strcmp(test->resource, "L3"))
__cpuid_count(0x10, 1, eax, ebx, ecx, edx);- else if (!strcmp(test->resource, "L2"))
__cpuid_count(0x10, 2, eax, ebx, ecx, edx);- else
return -EINVAL;
This would be same as (you need to make the func non-static though): level = get_cache_level(test->resource); if (level < 0) return -EINVAL; __cpuid_count(0x10, 4 - level, eax, ebx, ecx, edx);
- if (sparse_masks != ((ecx >> 3) & 1))
return -1;- /* Write checks initialization. */
- ret = get_cbm_mask(test->resource, &full_cache_mask);
- if (ret < 0)
return ret;- bit_center = count_bits(full_cache_mask) / 2;
- cont_mask = full_cache_mask >> bit_center;
- /* Contiguous mask write check. */
- snprintf(schemata, sizeof(schemata), "%lx", cont_mask);
- ret = write_schemata("", schemata, uparams->cpu, test->resource);
- if (ret)
return ret;- /*
* Non-contiguous mask write check. CBM has a 0xf hole approximately in the middle.* Output is compared with support information to catch any edge case errors.*/- noncont_mask = ~(full_cache_mask & (0xf << bit_center)) & full_cache_mask;
Why is the full_cache_mask & part needed here? It's not like the second and can grow bits outside of full_cache_mask even if that would overflow the full_cache_mask (it won't be testing hole then though but that problem happens also at the boundary condition one bit prior to overflowing the mask).
- snprintf(schemata, sizeof(schemata), "%lx", noncont_mask);
- ret = write_schemata("", schemata, uparams->cpu, test->resource);
- if (ret && sparse_masks)
ksft_print_msg("Non-contiguous CBMs supported but write failed\n");- else if (ret && !sparse_masks)
ksft_print_msg("Non-contiguous CBMs not supported and write failed as expected\n");- else if (!ret && !sparse_masks)
ksft_print_msg("Non-contiguous CBMs not supported but write succeeded\n");
Newline.
- return !ret == !sparse_masks;
+}
+static bool noncont_cat_feature_check(const struct resctrl_test *test) +{
- char res_path[PATH_MAX];
- struct stat statbuf;
- snprintf(res_path, sizeof(res_path), "%s/%s/%s", INFO_PATH,
test->resource, "sparse_masks");- if (stat(res_path, &statbuf))
return false;
This looks generic enough that validate_resctrl_feature_request() should be somehow adapted to cover also these cases. Perhaps it would be best to just split validate_resctrl_feature_request() into multiple functions.
- return test_resource_feature_check(test);
+}
struct resctrl_test l3_cat_test = { .name = "L3_CAT", .group = "CAT", @@ -357,3 +438,19 @@ struct resctrl_test l2_cat_test = { .feature_check = test_resource_feature_check, .run_test = cat_run_test, };
+struct resctrl_test l3_noncont_cat_test = {
- .name = "L3_NONCONT_CAT",
- .group = "NONCONT_CAT",
+struct resctrl_test l2_noncont_cat_test = {
- .name = "L2_NONCONT_CAT",
- .group = "NONCONT_CAT",
I think these should be grouped among "CAT" group because it well, tests CAT functionality. Why you think a separate group for them is needed?