On Thu, Jan 20, 2022 at 09:24:22AM +0100, Michal Hocko wrote:
> On Wed 19-01-22 20:25:54, Minchan Kim wrote:
> > On Wed, Jan 19, 2022 at 10:20:22AM +0100, Michal Hocko wrote:
> [...]
> > > What does prevent you from calling lru_cache_{disable,enable} this way
> > > with the existing implementation? AFAICS calls can be nested just fine.
> > > Or am I missing something?
> >
> > It just increases more IPI calls since we drain the lru cache
> > both upper layer and lower layer. That's I'd like to avoid
> > in this patch. Just disable lru cache one time for entire
> > allocation path.
>
> I do not follow. Once you call lru_cache_disable at the higher level
> then no new pages are going to be added to the pcp caches. At the same
> time existing caches are flushed so the inner lru_cache_disable will not
> trigger any new IPIs.
lru_cache_disable calls __lru_add_drain_all with force_all_cpus
unconditionally so keep calling the IPI.
