[LTP] [External] : [PATCH] device-drivers/cpufreq_boost: Don't hardcode to CPU0

[ALOK TIWARI]

On 6/27/2025 1:17 AM, Mike Tipton via ltp wrote:
> Some systems don't support boost on every CPU, such as on many Qualcomm
> chipsets. And if boost isn't supported on CPU0, then the test will fail
> since there's no performance improvement.
> 
> Instead of hardcoding CPU0, find the first CPU that belongs to a cpufreq
> policy with boost enabled.
> 
> Signed-off-by: Mike Tipton <mike.tipton@oss.qualcomm.com>
> ---
>   .../device-drivers/cpufreq/cpufreq_boost.c    | 58 ++++++++++++++++---
>   1 file changed, 50 insertions(+), 8 deletions(-)
> 
> diff --git a/testcases/kernel/device-drivers/cpufreq/cpufreq_boost.c b/testcases/kernel/device-drivers/cpufreq/cpufreq_boost.c
> index 67917b3fea25..5469126d2d12 100644
> --- a/testcases/kernel/device-drivers/cpufreq/cpufreq_boost.c
> +++ b/testcases/kernel/device-drivers/cpufreq/cpufreq_boost.c
> @@ -55,10 +55,14 @@ static int id = -1;
>   
>   static int boost_value;
>   
> -const char governor[]	= SYSFS_CPU_DIR "cpu0/cpufreq/scaling_governor";
> +static int cpu;
> +
> +static const char _governor[] = SYSFS_CPU_DIR "cpu%d/cpufreq/scaling_governor";
> +static char governor[64];
>   static char governor_name[16];
>   
> -const char maxspeed[]	= SYSFS_CPU_DIR "cpu0/cpufreq/scaling_max_freq";
> +static const char _maxspeed[] = SYSFS_CPU_DIR "cpu%d/cpufreq/scaling_max_freq";
> +static char maxspeed[64];
>   
>   static void check_set_turbo(char *file, char *off)
>   {
> @@ -84,6 +88,40 @@ static void cleanup(void)
>   		FILE_PRINTF(governor, "%s", governor_name);
>   }
>   
> +static int find_boost_cpu(void)
> +{
> +	char buf[64];
> +	int fd, i;
> +
> +	/*
> +	 * The files we're looking for only exist for acpi_cpufreq. Continue
> +	 * assuming CPU0 for intel_pstate.
> +	 */
> +	if (!strcmp(cdrv[id].name, "intel_pstate"))
> +		return 0;
> +
> +	for (i = 0;; i++) {
> +		snprintf(buf, sizeof(buf), SYSFS_CPU_DIR "cpu%d", i);
> +		fd = open(buf, O_RDONLY);
> +		if (fd == -1)
> +			break;
> +
> +		close(fd);
> +
> +		snprintf(buf, sizeof(buf), SYSFS_CPU_DIR "cpu%d/cpufreq/boost", i);
> +		fd = open(buf, O_RDONLY);
> +		if (fd == -1)
> +			continue;
> +
> +		close(fd);
> +		tst_resm(TINFO, "found boost-capable CPU (CPU%d)", i);
> +		return i;
> +	}
> +
> +	tst_resm(TINFO, "didn't find boost-capable CPU (assuming CPU0)");
> +	return 0;
> +}
> +
>   static void setup(void)
>   {
>   	int fd;
> @@ -109,6 +147,10 @@ static void setup(void)
>   	tst_resm(TINFO, "found '%s' driver, sysfs knob '%s'",
>   		cdrv[id].name, cdrv[id].file);
>   
> +	cpu = find_boost_cpu();
> +	snprintf(governor, sizeof(governor), _governor, cpu);
> +	snprintf(maxspeed, sizeof(governor), _maxspeed, cpu);

why sizeof(governor) not sizeof(maxspeed)

> +
>   	tst_sig(FORK, DEF_HANDLER, cleanup);
>   
>   	SAFE_FILE_SCANF(NULL, cdrv[i].file, "%d", &boost_value);
> @@ -120,16 +162,16 @@ static void setup(void)
>   	if (!strcmp(cdrv[i].name, "intel_pstate") && boost_value == cdrv[i].off)
>   		check_set_turbo(cdrv[i].file, cdrv[i].off_str);
>   

Thanks,
Alok