Re: [PATCH 7/9] mm/compaction: Get rid of RT ifdeffery

Sebastian Andrzej Siewior
2022-08-18T15:53:43Z

On 2022-08-18 10:55:28 [+0200], Rasmus Villemoes wrote:
> > --- a/mm/compaction.c
> > +++ b/mm/compaction.c
> > @@ -1727,11 +1727,7 @@ typedef enum {
> > * Allow userspace to control policy on scanning the unevictable LRU for
> > * compactable pages.
> > */
> > -#ifdef CONFIG_PREEMPT_RT
> > -int sysctl_compact_unevictable_allowed __read_mostly = 0;
> > -#else
> > -int sysctl_compact_unevictable_allowed __read_mostly = 1;
> > -#endif
> > +int sysctl_compact_unevictable_allowed __read_mostly = CONFIG_COMPACT_UNEVICTABLE_DEFAULT;
>
> Why introduce a Kconfig symbol for this, and not just spell the
> initializer "IS_ENABLED(CONFIG_PREEMPT_RT) ? 0 : 1" or simply
> "!IS_ENABLED(CONFIG_PREEMPT_RT)"?

The idea was to remove the CONFIG_PREEMPT_RT. However if this IS_ENABLED
is preferred, we can certainly do this.

> And if you do keep it in Kconfig, shouldn't the symbol be "depends on
> COMPACTION" so it doesn't needlessly appear in .config when
> !CONFIG_COMPACTION.

Sure, if we keep the Kconfig.

> Rasmus

Sebastian