Re: [PATCH v4 2/4] mm: failfast mode with __GFP_NORETRY in alloc_contig_range

Michal Hocko
2021-01-26T06:16:19Z

On Mon 25-01-21 14:12:02, Michal Hocko wrote:
> On Thu 21-01-21 09:55:00, Minchan Kim wrote:
> > Contiguous memory allocation can be stalled due to waiting
> > on page writeback and/or page lock which causes unpredictable
> > delay. It's a unavoidable cost for the requestor to get *big*
> > contiguous memory but it's expensive for *small* contiguous
> > memory(e.g., order-4) because caller could retry the request
> > in different range where would have easy migratable pages
> > without stalling.
> >
> > This patch introduce __GFP_NORETRY as compaction gfp_mask in
> > alloc_contig_range so it will fail fast without blocking
> > when it encounters pages needed waiting.
>
> I am not against controling how hard this allocator tries with gfp mask
> but this changelog is rather void on any data and any user.

OK, I can see that a user is in the last patch.

--
Michal Hocko
SUSE Labs