Re: [RFC PATCH v3 04/15] rcu: Add a small-width RCU watching counter debug option

[Valentin Schneider]

On 22/11/24 04:53, Paul E. McKenney wrote:
> On Tue, Nov 19, 2024 at 04:34:51PM +0100, Valentin Schneider wrote:
>> +config RCU_DYNTICKS_TORTURE
>> +	bool "Minimize RCU dynticks counter size"
>> +	depends on RCU_EXPERT
>> +	default n
>> +	help
>> +	  This option controls the width of the dynticks counter.
>> +
>> +	  Lower values will make overflows more frequent, which will increase
>> +	  the likelihood of extending grace-periods. This option sets the width
>> +	  to its minimum usable value.
>
> The second sentence ("Lower values ...") sounds at first reading like
> this Kconfig option directly controls the width.  The third sentence sets
> things straight, but the reader might well be irretrievably confused by
> that point.  How about something like this instead?
>
>       help
>         This option sets the width of the dynticks counter to its
>         minimum usable value.  This minimum width greatly increases
>         the probability of flushing out bugs involving counter wrap,
>         but it also increases the probability of extending grace period
>         durations.  This Kconfig option should therefore be avoided in
>         production due to the consequent increased probability of OOMs.
>
>         This has no value for production and is only for testing.
>

Much better, I'll take that, thank you!

>>  endmenu # "RCU Debugging"
>> --
>> 2.43.0
>>