linux-kernel - Re: [PATCH] sched/Documentation: Add RT_RUNTIME

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Date: Fri, 19 Apr 2024 16:51:56 +0800
From: Zhang Qiao <zhangqiao22@...wei.com>
To: Bagas Sanjaya <bagasdotme@...il.com>
CC: <mingo@...nel.org>, <chrubis@...e.cz>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Steven Rostedt <rostedt@...dmis.org>, Peter
 Zijlstra <peterz@...radead.org>, <corbet@....net>
Subject: Re: [PATCH] sched/Documentation: Add RT_RUNTIME_SHARE documentation



在 2024/4/12 10:50, Bagas Sanjaya 写道:
> On Wed, Jan 31, 2024 at 08:32:38PM +0800, Zhang Qiao wrote:
>> +2.4 RT_RUNTIME_SHARE sched feature
>> +----------------------------
> 
> htmldocs build reports new warning:
> 
> Documentation/scheduler/sched-rt-group.rst:151: WARNING: Title underline too short.
> 
> 2.4 RT_RUNTIME_SHARE sched feature
> ----------------------------
> 
> I have to extend the underline:
> 
> ---- >8 ----
> diff --git a/Documentation/scheduler/sched-rt-group.rst b/Documentation/scheduler/sched-rt-group.rst
> index 4d8eceb71f5ed8..751113fcd35850 100644
> --- a/Documentation/scheduler/sched-rt-group.rst
> +++ b/Documentation/scheduler/sched-rt-group.rst
> @@ -148,7 +148,7 @@ For now, this can be simplified to just the following (but see Future plans):
>     \Sum_{i} runtime_{i} <= global_runtime
>  
>  2.4 RT_RUNTIME_SHARE sched feature
> -----------------------------
> +----------------------------------
>  
>  RT_RUNTIME_SHARE allows a cpu borrows rt-runtime from other cpus if it runs
>  out of its own rt-runtime.
> 
> Wording suggestions below.

Hi, Bagas，
Thanks for you suggestions, i will update in v2.


Zhang Qiao.

> 
>> +
>> +RT_RUNTIME_SHARE allows a cpu borrows rt-runtime from other cpus if it runs
> "... to borrow rt-runtime ..."
>> +out of its own rt-runtime.
>> +
>> +With this feature enabled, a rt-task probably hits 100% cpu usage and starves
> "... a rt-task may hit ... and can stall other per-cpu tasks ..."
>> +per-cpu tasks like kworkers, as a result, it may hang up the whole system.
> "..., which lead into system hang."
>> +Therefore, in order to avoid such exception, recommand to disable this feature
>> +by default unless you really know what you're up to.
> "Thus, it is advised to disable this feature by default to avoid aforementioned
> issue unless you know what you're doing."
> 
> Thanks.
>