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

On Mon 25-01-21 14:12:02, Michal Hocko wrote:

On Thu 21-01-21 09:55:00, Minchan Kim wrote:

quoted

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