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authorReinette Chatre <reinette.chatre@intel.com>2024-10-24 14:18:49 -0700
committerShuah Khan <skhan@linuxfoundation.org>2024-11-04 17:02:03 -0700
commitf77b9672536e581c945b2623b521a284fdbf75ff (patch)
tree7c9055082837b5ede6a1ba98b2ecaabfe66610e7
parent3cb3f0b8755919648281064d44c06319743db343 (diff)
selftests/resctrl: Use cache size to determine "fill_buf" buffer size
By default the MBM and MBA tests use the "fill_buf" benchmark to read from a buffer with the goal to measure the memory bandwidth generated by this buffer access. Care should be taken when sizing the buffer used by the "fill_buf" benchmark. If the buffer is small enough to fit in the cache then it cannot be expected that the benchmark will generate much memory bandwidth. For example, on a system with 320MB L3 cache the existing hardcoded default of 250MB is insufficient. Use the measured cache size to determine a buffer size that can be expected to trigger memory access while keeping the existing default as minimum, now renamed to MINIMUM_SPAN, that has been appropriate for testing so far. Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
-rw-r--r--tools/testing/selftests/resctrl/fill_buf.c13
-rw-r--r--tools/testing/selftests/resctrl/mba_test.c7
-rw-r--r--tools/testing/selftests/resctrl/mbm_test.c7
-rw-r--r--tools/testing/selftests/resctrl/resctrl.h3
-rw-r--r--tools/testing/selftests/resctrl/resctrl_tests.c2
5 files changed, 28 insertions, 4 deletions
diff --git a/tools/testing/selftests/resctrl/fill_buf.c b/tools/testing/selftests/resctrl/fill_buf.c
index 380cc35f10c6..19a01a52dc1a 100644
--- a/tools/testing/selftests/resctrl/fill_buf.c
+++ b/tools/testing/selftests/resctrl/fill_buf.c
@@ -129,3 +129,16 @@ unsigned char *alloc_buffer(size_t buf_size, bool memflush)
return buf;
}
+
+ssize_t get_fill_buf_size(int cpu_no, const char *cache_type)
+{
+ unsigned long cache_total_size = 0;
+ int ret;
+
+ ret = get_cache_size(cpu_no, cache_type, &cache_total_size);
+ if (ret)
+ return ret;
+
+ return cache_total_size * 2 > MINIMUM_SPAN ?
+ cache_total_size * 2 : MINIMUM_SPAN;
+}
diff --git a/tools/testing/selftests/resctrl/mba_test.c b/tools/testing/selftests/resctrl/mba_test.c
index 74d95c460bd0..bf37f3555660 100644
--- a/tools/testing/selftests/resctrl/mba_test.c
+++ b/tools/testing/selftests/resctrl/mba_test.c
@@ -182,7 +182,12 @@ static int mba_run_test(const struct resctrl_test *test, const struct user_param
fill_buf.memflush = uparams->fill_buf->memflush;
param.fill_buf = &fill_buf;
} else if (!uparams->benchmark_cmd[0]) {
- fill_buf.buf_size = DEFAULT_SPAN;
+ ssize_t buf_size;
+
+ buf_size = get_fill_buf_size(uparams->cpu, "L3");
+ if (buf_size < 0)
+ return buf_size;
+ fill_buf.buf_size = buf_size;
fill_buf.memflush = true;
param.fill_buf = &fill_buf;
}
diff --git a/tools/testing/selftests/resctrl/mbm_test.c b/tools/testing/selftests/resctrl/mbm_test.c
index 72261413c868..4224f8ce3538 100644
--- a/tools/testing/selftests/resctrl/mbm_test.c
+++ b/tools/testing/selftests/resctrl/mbm_test.c
@@ -149,7 +149,12 @@ static int mbm_run_test(const struct resctrl_test *test, const struct user_param
fill_buf.memflush = uparams->fill_buf->memflush;
param.fill_buf = &fill_buf;
} else if (!uparams->benchmark_cmd[0]) {
- fill_buf.buf_size = DEFAULT_SPAN;
+ ssize_t buf_size;
+
+ buf_size = get_fill_buf_size(uparams->cpu, "L3");
+ if (buf_size < 0)
+ return buf_size;
+ fill_buf.buf_size = buf_size;
fill_buf.memflush = true;
param.fill_buf = &fill_buf;
}
diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index 032cd9ebd761..a553fe975938 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -41,7 +41,7 @@
#define BENCHMARK_ARGS 64
-#define DEFAULT_SPAN (250 * MB)
+#define MINIMUM_SPAN (250 * MB)
/*
* fill_buf_param: "fill_buf" benchmark parameters
@@ -169,6 +169,7 @@ int perf_event_open(struct perf_event_attr *hw_event, pid_t pid, int cpu,
unsigned char *alloc_buffer(size_t buf_size, bool memflush);
void mem_flush(unsigned char *buf, size_t buf_size);
void fill_cache_read(unsigned char *buf, size_t buf_size, bool once);
+ssize_t get_fill_buf_size(int cpu_no, const char *cache_type);
int initialize_read_mem_bw_imc(void);
int measure_read_mem_bw(const struct user_params *uparams,
struct resctrl_val_param *param, pid_t bm_pid);
diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
index 24daf76b4039..3335af815b21 100644
--- a/tools/testing/selftests/resctrl/resctrl_tests.c
+++ b/tools/testing/selftests/resctrl/resctrl_tests.c
@@ -189,7 +189,7 @@ static struct fill_buf_param *alloc_fill_buf_param(struct user_params *uparams)
ksft_exit_skip("Unable to parse benchmark buffer size.\n");
}
} else {
- fill_param->buf_size = DEFAULT_SPAN;
+ fill_param->buf_size = MINIMUM_SPAN;
}
if (uparams->benchmark_cmd[2] && *uparams->benchmark_cmd[2] != '\0') {