Right now the test gives false results on kernels since v3.9. That's because
of the following commit:
acpi-cpufreq: set current frequency based on target P-State
8673b83bf2f013379453b4779047bf3c6ae387e4
So the sysfs 'cpuinfo_cur_freq' gives target frequency which is set by
acpi-cpufreq driver itself.
One possible way to find out that boost is actually off is to calculate
average integer counter frequency on the tested CPU (this is how is done in
the patch). Results show that the calculated counter frequency is close to
actual CPU frequency if no other threads with the highest priority are
running on the test CPU. The above condition is true for most cases.
Another way is to utilize MSR APERF/MPERF registers and TSC in Intel
processors. That can be done by reading MSR from /dev/cpu/0/msr. But
this will require additional checks in configure of asm/msr-index.h file
and built-in non-portable __get_cpuid() function, also reading TSC register
using asm instructions. And who knows what else for AMD silicons.
Let's not complicate things too much and use the first method.
Signed-off-by: Alexey Kodanev <alexey.koda...@oracle.com>
---
.../kernel/device-drivers/acpi/ltp_acpi_cpufreq.c | 64 +++++++++++--------
1 files changed, 37 insertions(+), 27 deletions(-)
diff --git a/testcases/kernel/device-drivers/acpi/ltp_acpi_cpufreq.c
b/testcases/kernel/device-drivers/acpi/ltp_acpi_cpufreq.c
index 73fb430..d3d131c 100644
--- a/testcases/kernel/device-drivers/acpi/ltp_acpi_cpufreq.c
+++ b/testcases/kernel/device-drivers/acpi/ltp_acpi_cpufreq.c
@@ -20,9 +20,12 @@
* Check support for disabling dynamic overclocking in acpi_cpufreq driver.
* Required Linux 3.7+.
*
- * The test loads CPU0 in a thread. When the loading approaches to the end
- * (2/3 elapsed), the test will check processor frequency. if boost is enabled
- * we can get a slightly higher speed under load.
+ * The test loads CPU0 in a thread. It will calc counter frequency on each
+ * load-run with and without boost-disable bit. If boost is enabled we can
+ * get a slightly higher counter frequency. Use simple counter and don't rely
+ * on sysfs cpuinfo_cur_freq value, because after the upstream commit
+ * 8673b83bf2f013379453b4779047bf3c6ae387e4, current cpu frequency becomes
+ * target cpu frequency.
*/
#define _GNU_SOURCE
@@ -30,9 +33,11 @@
#include <stdlib.h>
#include <sched.h>
#include <sys/time.h>
+#include <sys/resource.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/stat.h>
+#include <unistd.h>
#include <fcntl.h>
#include "test.h"
@@ -54,6 +59,8 @@ const char setspeed[] = SYSFS_CPU_DIR
"cpu0/cpufreq/scaling_setspeed";
const char curspeed[] = SYSFS_CPU_DIR "cpu0/cpufreq/cpuinfo_cur_freq";
const char maxspeed[] = SYSFS_CPU_DIR "cpu0/cpufreq/scaling_max_freq";
+const int units = 1000000; /* Mhz */
+
static void cleanup(void)
{
SAFE_FILE_PRINTF(NULL, boost, "%d", boost_value);
@@ -90,6 +97,8 @@ static void setup(void)
CPU_SET(0, &set);
if (sched_setaffinity(0, sizeof(cpu_set_t), &set) < 0)
tst_brkm(TBROK | TERRNO, cleanup, "failed to set CPU0");
+
+ setpriority(PRIO_PROCESS, getpid(), -20);
}
static void set_speed(int freq)
@@ -110,26 +119,27 @@ void *thread_fn(void *val)
{
struct timeval tv_start;
struct timeval tv_end;
- int i, res = 0;
- intptr_t timeout = (intptr_t) val;
+ int i;
+ unsigned long long res = 0;
+ intptr_t timeout = (intptr_t) val, ret;
gettimeofday(&tv_start, NULL);
tst_resm(TINFO, "load CPU0 for %ld sec...", timeout);
do {
- for (i = 1; i < 10000; ++i)
- res += i * i;
+ for (i = 0; i < units; ++i)
+ ++res;
gettimeofday(&tv_end, NULL);
- sched_yield();
} while ((tv_end.tv_sec - tv_start.tv_sec) < timeout);
- tst_resm(TINFO, "CPU0 load done: insignificant value '%d'", res);
+ ret = res / units / timeout;
- return NULL;
+ return ((void *)ret);
}
static int load_cpu(intptr_t timeout)
{
+ void *ret;
pthread_t thread_id;
if (pthread_create(&thread_id, 0, thread_fn,
@@ -139,37 +149,37 @@ static int load_cpu(intptr_t timeout)
__FILE__, __LINE__);
}
- sleep(2 * timeout / 3);
-
- int cur_freq;
- SAFE_FILE_SCANF(cleanup, curspeed, "%d", &cur_freq);
- tst_resm(TINFO, "got cpu freq under load: %d", cur_freq);
-
- pthread_join(thread_id, NULL);
+ pthread_join(thread_id, &ret);
- return cur_freq;
+ return (intptr_t)ret;
}
static void test_run(void)
{
- int cur_freq, max_freq;
+ int boost_freq, boost_off_freq, max_freq;
SAFE_FILE_SCANF(cleanup, maxspeed, "%d", &max_freq);
set_speed(max_freq);
+ /* make sure the process gets to run with the highest priority */
+ load_cpu(5);
+
/* Enable boost */
if (boost_value == 0)
SAFE_FILE_PRINTF(cleanup, boost, "1");
- cur_freq = load_cpu(30);
- tst_resm((cur_freq >= max_freq) ? TPASS : TFAIL,
- "compare current speed %d and max speed %d",
- cur_freq, max_freq);
+ boost_freq = load_cpu(12);
+ tst_resm(TINFO, "avg counter freq with boost enabled: %d MHz",
boost_freq);
/* Disable boost */
SAFE_FILE_PRINTF(cleanup, boost, "0");
- cur_freq = load_cpu(30);
- tst_resm((cur_freq < max_freq) ? TPASS : TFAIL,
- "compare current speed %d and max speed %d",
- cur_freq, max_freq);
+ boost_off_freq = load_cpu(12);
+
+ tst_resm(TINFO, "avg counter freq with boost disabled: %d MHz",
boost_off_freq);
+
+ boost_off_freq *= 1.01;
+
+ tst_resm((boost_freq > boost_off_freq) ? TPASS : TFAIL,
+ "compare boost speed %d and speed without boost + 1%% %d",
+ boost_freq, boost_off_freq);
}
int main(int argc, char *argv[])
--
1.7.1
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