Re: [RFC][PATCH 1/2] mm: use MIGRATE_HIGHATOMIC as late as possible

[Michal Hocko]

On Tue 07-03-17 19:03:39, Xishi Qiu wrote:
> On 2017/3/7 18:47, Michal Hocko wrote:
> 
> > On Tue 07-03-17 18:33:53, Xishi Qiu wrote:
> >> MIGRATE_HIGHATOMIC page blocks are reserved for an atomic
> >> high-order allocation, so use it as late as possible.
> > 
> > Why is this better? Are you seeing any problem which this patch
> > resolves? In other words the patch description should explain why not
> > only what (that is usually clear from looking at the diff).
> > 
> 
> Hi Michal,
> 
> I have not see any problem yet, I think if we reserve more high order
> pageblocks, the more success rate we will get when meet an atomic
> high-order allocation, right?

Please make sure you measure your changes under different workloads and
present numbers in the changelog when you are touch such a subtle things
like memory reserves. Ideas that might sound they make sense can turn
out to behave differently in the real life.
-- 
Michal Hocko
SUSE Labs