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

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