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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Fri, 25 Feb 2022 16:39:38 +0100
Message-ID: <CAJZ5v0gLn=EEsLLZBtFUKA9SkK88S1HQxj_Z11sPgnRE9T_RmQ@mail.gmail.com>
Subject: Re: [PATCH 3/4] acpi: exsystem: Warn about sleeps greater than 50 ms
To:     Paul Menzel <pmenzel@molgen.mpg.de>
Cc:     Robert Moore <robert.moore@intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Len Brown <lenb@kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" <devel@acpica.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Thu, Feb 24, 2022 at 12:38 PM Paul Menzel <pmenzel@molgen.mpg.de> wrote:
>
> Quick boottime is important, so warn about sleeps greater than 50 ms in
> ACPI.
>
> 50 ms is still long compared to distribution Linux kernels reaching initrd
> in 350 ms, so should probably changed to 10 ms, so people are aware
> about this.
>
> Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>

First off, as ACPICA material, this should be submitted to the
upstream project via https://github.com/acpica/acpica/.

> ---
>  drivers/acpi/acpica/exsystem.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/acpi/acpica/exsystem.c b/drivers/acpi/acpica/exsystem.c
> index 00f66af31ffa..bdffb8aac05c 100644
> --- a/drivers/acpi/acpica/exsystem.c
> +++ b/drivers/acpi/acpica/exsystem.c
> @@ -167,6 +167,11 @@ acpi_status acpi_ex_system_do_sleep(u64 how_long_ms)
>
>         acpi_ex_exit_interpreter();
>
> +       if (how_long_ms > 50) {
> +               ACPI_WARNING((AE_INFO,

Second, the log level is somewhat high for something like this.

> +                   "Time parameter %llu > 50 ms. Please contact firmware vendor for more responsive system.", how_long_ms));

Also, I would rephrase the warning message to something like "Firmware
issue: Excessive delay (%llu ms) in ACPI Control Method".

> +       }
> +
>         /*
>          * For compatibility with other ACPI implementations and to prevent
>          * accidental deep sleeps, limit the sleep time to something reasonable.
> --
> 2.35.1
>