[SRU][F][PATCH 1/1] Ubuntu: [Config] CONFIG_PSI is enabled by default, but creates additional overhead on s390x, hence should be disabled by default on s390x only.

[Kleber Souza]

On 05.05.20 21:20, frank.heimes at canonical.com wrote:
> From: Frank Heimes <frank.heimes at canonical.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1876044
> 
> PSI is always enabled in Ubuntu due to 'CONFIG_PSI_DEFAULT_DISABLED=n' / 'not set'.
> This causes a performance degradation for popular workloads like web serving (nginx) due to additional overhead.
> Hence IBM is requesting to change this option to yes for s390x: 'CONFIG_PSI_DEFAULT_DISABLED=y'.
> CONFIG_PSI is already set to yes, and should stay.
> 
> Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
> ---
>  debian.master/config/annotations          | 4 +++-
>  debian.master/config/config.common.ubuntu | 2 +-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/debian.master/config/annotations b/debian.master/config/annotations
> index dd6481141e9f..20fd9e21bc72 100644
> --- a/debian.master/config/annotations
> +++ b/debian.master/config/annotations
> @@ -10316,7 +10316,9 @@ CONFIG_TASK_DELAY_ACCT                          policy<{'amd64': 'y', 'arm64': '
>  CONFIG_TASK_XACCT                               policy<{'amd64': 'y', 'arm64': 'y', 'armhf': 'y', 'i386': 'y', 'ppc64el': 'y', 's390x': 'y'}>
>  CONFIG_TASK_IO_ACCOUNTING                       policy<{'amd64': 'y', 'arm64': 'y', 'armhf': 'y', 'i386': 'y', 'ppc64el': 'y', 's390x': 'y'}>
>  CONFIG_PSI                                      policy<{'amd64': 'y', 'arm64': 'y', 'armhf': 'y', 'i386': 'y', 'ppc64el': 'y', 's390x': 'y'}>
> -CONFIG_PSI_DEFAULT_DISABLED                     policy<{'amd64': 'n', 'arm64': 'n', 'armhf': 'n', 'i386': 'n', 'ppc64el': 'n', 's390x': 'n'}>
> +CONFIG_PSI_DEFAULT_DISABLED                     policy<{'amd64': 'n', 'arm64': 'n', 'armhf': 'n', 'i386': 'n', 'ppc64el': 'n', 's390x': 'y'}>

Hi Frank,

The annotations file is being changed only for s390x but the config change
below will affect all architectures. Should the config change be applied
only to 'debian.master/config/s390x/config.common.s390x'?


Kleber

> +
> +CONFIG_PSI_DEFAULT_DISABLED                     mark<LP:1876044>
>  
>  # Menu: General setup >> CPU/Task time and stats accounting >> Cputime accounting
>  CONFIG_TICK_CPU_ACCOUNTING                      policy<{'amd64': 'y', 'arm64': 'y', 'armhf': 'y', 'i386': 'y', 'ppc64el': 'y', }>
> diff --git a/debian.master/config/config.common.ubuntu b/debian.master/config/config.common.ubuntu
> index f502f2bdfa07..115590e89d73 100644
> --- a/debian.master/config/config.common.ubuntu
> +++ b/debian.master/config/config.common.ubuntu
> @@ -7567,7 +7567,7 @@ CONFIG_PSAMPLE=m
>  CONFIG_PSERIES_CPUIDLE=y
>  CONFIG_PSERIES_ENERGY=m
>  CONFIG_PSI=y
> -# CONFIG_PSI_DEFAULT_DISABLED is not set
> +CONFIG_PSI_DEFAULT_DISABLED=y
>  # CONFIG_PSTORE_842_COMPRESS is not set
>  CONFIG_PSTORE_COMPRESS=y
>  CONFIG_PSTORE_COMPRESS_DEFAULT="deflate"
>