Re: [PATCH v6 1/2] memory_hotplug: Free pages as higher order

[Arun KS]

On 2018-11-07 01:38, Michal Hocko wrote:
> On Tue 06-11-18 21:01:29, Arun KS wrote:
> > On 2018-11-06 19:36, Michal Hocko wrote:
> > > On Tue 06-11-18 11:33:13, Arun KS wrote:
> > > > When free pages are done with higher order, time spend on
> > > > coalescing pages by buddy allocator can be reduced. With
> > > > section size of 256MB, hot add latency of a single section
> > > > shows improvement from 50-60 ms to less than 1 ms, hence
> > > > improving the hot add latency by 60%. Modify external
> > > > providers of online callback to align with the change.
> > > >
> > > > This patch modifies totalram_pages, zone->managed_pages and
> > > > totalhigh_pages outside managed_page_count_lock. A follow up
> > > > series will be send to convert these variable to atomic to
> > > > avoid readers potentially seeing a store tear.
> > >
> > > Is there any reason to rush this through rather than wait for counters
> > > conversion first?
> >
> > Sure Michal.
> >
> > Conversion patch, https://patchwork.kernel.org/cover/10657217/ is 
> > currently
> > incremental to this patch.
>
> The ordering should be other way around. Because as things stand with
> this patch first it is possible to introduce a subtle race prone
> updates. As I've said I am skeptical the race would matter, really, but
> there is no real reason to risk for that. Especially when you have the
> other (first) half ready.

Makes sense. I have rebased the preparatory patch on top of -rc1.
https://patchwork.kernel.org/patch/10670787/

Regards,
Arun