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

From: Valentin Schneider
Date: Fri Nov 22 2024 - 08:57:09 EST


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
>>