[LTP] [PATCH 1/1] lib: Remove CONFIG_LATENCYTOP as "slow" kernel option

[LTP] [PATCH 1/1] lib: Remove CONFIG_LATENCYTOP as "slow" kernel option

[Petr Vorel]

CONFIG_LATENCYTOP enables a kernel latency tracking infrastructure that is
used by the "latencytop" userspace tool. The latency that is tracked is not
else consuming CPU), but instead, it is the latency an application encounters
because the kernel sleeps on its behalf for various reasons.

This code tracks 2 levels of statistics:
1) System level latency
2) Per process latency

IMHO this option is safe unless one runs latencytop userspace tool while
testing LTP.

Motivation for this is the openSUSE and some SLES kernels use
CONFIG_LATENCYTOP and all tests are working with a default timeout.
starvation.c is disabled with TCONF on slow kernels, which previously
worked well on kernels with CONFIG_LATENCYTOP.

Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
NOTE: I would like to get this merged before upcoming release.

Kind regards,
Petr

 lib/tst_kconfig.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
index 66402e370d..9bcd577210 100644
--- a/lib/tst_kconfig.c
+++ b/lib/tst_kconfig.c
@@ -644,7 +644,6 @@ static struct tst_kconfig_var slow_kconfigs[] = {
 	TST_KCONFIG_INIT("CONFIG_KASAN"),
 	TST_KCONFIG_INIT("CONFIG_SLUB_RCU_DEBUG"),
 	TST_KCONFIG_INIT("CONFIG_TRACE_IRQFLAGS"),
-	TST_KCONFIG_INIT("CONFIG_LATENCYTOP"),
 	TST_KCONFIG_INIT("CONFIG_DEBUG_NET"),
 	TST_KCONFIG_INIT("CONFIG_EXT4_DEBUG"),
 	TST_KCONFIG_INIT("CONFIG_QUOTA_DEBUG"),
-- 
2.47.1


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Re: [LTP] [PATCH 1/1] lib: Remove CONFIG_LATENCYTOP as "slow" kernel option

[Li Wang]

On Mon, Jan 20, 2025 at 10:34 PM Petr Vorel <pvorel@suse.cz> wrote:

> CONFIG_LATENCYTOP enables a kernel latency tracking infrastructure that is
> used by the "latencytop" userspace tool. The latency that is tracked is not
> else consuming CPU), but instead, it is the latency an application
> encounters
> because the kernel sleeps on its behalf for various reasons.
>
> This code tracks 2 levels of statistics:
> 1) System level latency
> 2) Per process latency
>
> IMHO this option is safe unless one runs latencytop userspace tool while
> testing LTP.
>
> Motivation for this is the openSUSE and some SLES kernels use
> CONFIG_LATENCYTOP and all tests are working with a default timeout.
> starvation.c is disabled with TCONF on slow kernels, which previously
> worked well on kernels with CONFIG_LATENCYTOP.
>
> Signed-off-by: Petr Vorel <pvorel@suse.cz>
>

Thanks for removing this, I didn't do much more evaluation on that config
while adding it to tst_has_slow_kconfig().

Reviewed-by: Li Wang <liwang@redhat.com>

---
> NOTE: I would like to get this merged before upcoming release.
>
> Kind regards,
> Petr
>
>  lib/tst_kconfig.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
> index 66402e370d..9bcd577210 100644
> --- a/lib/tst_kconfig.c
> +++ b/lib/tst_kconfig.c
> @@ -644,7 +644,6 @@ static struct tst_kconfig_var slow_kconfigs[] = {
>         TST_KCONFIG_INIT("CONFIG_KASAN"),
>         TST_KCONFIG_INIT("CONFIG_SLUB_RCU_DEBUG"),
>         TST_KCONFIG_INIT("CONFIG_TRACE_IRQFLAGS"),
> -       TST_KCONFIG_INIT("CONFIG_LATENCYTOP"),
>         TST_KCONFIG_INIT("CONFIG_DEBUG_NET"),
>         TST_KCONFIG_INIT("CONFIG_EXT4_DEBUG"),
>         TST_KCONFIG_INIT("CONFIG_QUOTA_DEBUG"),
> --
> 2.47.1
>
>

-- 
Regards,
Li Wang

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Re: [LTP] [PATCH 1/1] lib: Remove CONFIG_LATENCYTOP as "slow" kernel option

[Cyril Hrubis]

Hi!
Reviewed-by: Cyril Hrubis <chrubis@suse.cz>

-- 
Cyril Hrubis
chrubis@suse.cz

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Re: [LTP] [PATCH 1/1] lib: Remove CONFIG_LATENCYTOP as "slow" kernel option

[Petr Vorel]

Hi all,

Li, Cyril, thanks for your review, merged!

Kind regards,
Petr

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