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SubjectRe: [PATCH v5 1/3] printk: Fix LOG_CPU_MAX_BUF_SHIFT when BASE_SMALL is enabled
On Tue, Feb 13, 2024 at 4:01 AM Yoann Congal <yoann.congal@smile.fr> wrote:
>
>
>
> Le 11/02/2024 à 00:41, Masahiro Yamada a écrit :
> > On Thu, Feb 8, 2024 at 2:10 AM Yoann Congal <yoann.congal@smilefr> wrote:
> >>
> >> LOG_CPU_MAX_BUF_SHIFT default value depends on BASE_SMALL:
> >> config LOG_CPU_MAX_BUF_SHIFT
> >> default 12 if !BASE_SMALL
> >> default 0 if BASE_SMALL
> >> But, BASE_SMALL is a config of type int and "!BASE_SMALL" is always
> >> evaluated to true whatever is the value of BASE_SMALL.
> >>
> >> This patch fixes this by using the correct conditional operator for int
> >> type : BASE_SMALL != 0.
> >>
> >> Note: This changes CONFIG_LOG_CPU_MAX_BUF_SHIFT=12 to
> >> CONFIG_LOG_CPU_MAX_BUF_SHIFT=0 for BASE_SMALL defconfigs, but that will
> >> not be a big impact due to this code in kernel/printk/printk.c:
> >> /* by default this will only continue through for large > 64 CPUs */
> >> if (cpu_extra <= __LOG_BUF_LEN / 2)
> >> return;
> >> Systems using CONFIG_BASE_SMALL and having 64+ CPUs should be quite
> >> rare.
> >>
> >> John Ogness <john.ogness@linutronix.de> (printk reviewer) wrote:
> >>> For printk this will mean that BASE_SMALL systems were probably
> >>> previously allocating/using the dynamic ringbuffer and now they will
> >>> just continue to use the static ringbuffer. Which is fine and saves
> >>> memory (as it should).
> >>
> >> Petr Mladek <pmladek@suse.com> (printk maintainer) wrote:
> >>> More precisely, it allocated the buffer dynamically when the sum
> >>> of per-CPU-extra space exceeded half of the default static ring
> >>> buffer. This happened for systems with more than 64 CPUs with
> >>> the default config values.
> >>
> >> Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
> >> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> >> Closes: https://lore.kernel.org/all/CAMuHMdWm6u1wX7efZQf=2XUAHascps76YQac6rdnQGhc8nop_Q@mail.gmail.com/
> >> Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
> >> Closes: https://lore.kernel.org/all/f6856be8-54b7-0fa0-1d17-39632bf29ada@oracle.com/
> >> Fixes: 4e244c10eab3 ("kconfig: remove unneeded symbol_empty variable")
> >>
> >
> >
> >
> > All the Reviewed-by tags are dropped every time, annoyingly.
>
> Hi!
>
> Was I supposed to gather these tags from patch version N to patch version N+1?
> In that case, I'm sorry, I did not know that :-/
> Patch 1/3 is exactly the same but patch 2/3 is equivalent but different. Is there a rule written somewhere about when carrying the tags across revision and when not? (I could not find it)


I do not know any written rules either.


In my experience, people carry tags
when changes since the previous version are small.





--
Best Regards
Masahiro Yamada

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