Re: [LTP] [Patch V2] lib: multiply the max_runtime if detect kernel debug options

[Cyril Hrubis <chrubis@suse.cz>]

Hi!
> +/*
> + * List of debug-kernel config options that may degrade performance when enabled.
> + */
> +static const char * const tst_kconf_debug_options[][2] = {
> +	{"CONFIG_PROVE_LOCKING=y", NULL},
> +	{"CONFIG_LOCKDEP=y", NULL},
> +	{"CONFIG_DEBUG_SPINLOCK=y", NULL},
> +	{"CONFIG_DEBUG_RT_MUTEXES=y", NULL},
> +	{"CONFIG_DEBUG_MUTEXES=y", NULL},
> +	{"CONFIG_DEBUG_PAGEALLOC=y", NULL},
> +	{"CONFIG_KASAN=y", NULL},
> +	{"CONFIG_SLUB_RCU_DEBUG=y", NULL},
> +	{"CONFIG_TRACE_IRQFLAGS=y", NULL},
> +	{"CONFIG_LATENCYTOP=y", NULL},
> +	{"CONFIG_DEBUG_NET=y", NULL},
> +	{"CONFIG_EXT4_DEBUG=y", NULL},
> +	{"CONFIG_QUOTA_DEBUG=y", NULL},
> +	{"CONFIG_FAULT_INJECTION=y", NULL},
> +	{"CONFIG_DEBUG_OBJECTS=y", NULL},
> +	{NULL, NULL}
> +};
> +
> +int tst_any_kconfig_debug_enabled(void);
> +
>  #endif	/* TST_KCONFIG_H__ */
> diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
> index 6d6b1da18..a99147a62 100644
> --- a/lib/tst_kconfig.c
> +++ b/lib/tst_kconfig.c
> @@ -631,3 +631,17 @@ void tst_kcmdline_parse(struct tst_kcmdline_var params[], size_t params_len)
>  
>  	SAFE_FCLOSE(f);
>  }
> +
> +int tst_any_kconfig_debug_enabled(void)
> +{
> +	int i;
> +
> +	for (i = 0; tst_kconf_debug_options[i][0] != NULL; i++) {
> +		if(!tst_kconfig_check(tst_kconf_debug_options[i])) {

I suppose that using tst_kconfig_check() here has a few flaws.

First of all we are passing it one by one, which means that we are
parsing the .config over and over. Also the tst_kconfig_check() is
tailored to a special usecase where each of the strings is treated as an
expression, which is slower. And lastly but not least will also print
the "Constraint '%s' not satisfied" line for each option that is not set.

We already have the tst_kconfig_var structure and tst_kconfig_read() so
it would make more sense to use the simple interface as:

static struct tst_kconfig_var debug_kconfigs[] = {
	TST_KCONFIG_INIT("CONFIG_PROVE_LOCKING"),
	...
};

And then loop over the results as:

	int is_debug_kernel = 0;

	tst_kconfig_read(debug_kconfigs, ARRAY_SIZE(debug_kconfigs));

	for (i = 0; i < ARRAY_SIZE(debug_kconfigs); i++) {
		if (debug_kconfigs[i].choice == 'y') {
			tst_res(TINFO,
				"%s kernel debug option detected",
				debug_kconfigs[i].id);
				is_debug_kernel = 1;
		}
	}

> +			tst_res(TINFO, "Detected kernel debug options. Likely running on a debug kernel");
> +			return 1;
> +		}
> +	}
> +	return 0;
> +}
> diff --git a/lib/tst_test.c b/lib/tst_test.c
> index 8db554dea..00ac8f4f3 100644
> --- a/lib/tst_test.c
> +++ b/lib/tst_test.c
> @@ -555,6 +555,9 @@ static int multiply_runtime(int max_runtime)
>  
>  	parse_mul(&runtime_mul, "LTP_RUNTIME_MUL", 0.0099, 100);
>  
> +	if (tst_any_kconfig_debug_enabled())
> +		max_runtime *= 4;
> +
>  	return max_runtime * runtime_mul;
>  }
>  
> -- 
> 2.47.0
> 

-- 
Cyril Hrubis
chrubis@suse.cz

-- 
Mailing list info: https://lists.linux.it/listinfo/ltp