Re: [PATCH 3/3] hugetlbfs: don't retry when pool page allocations start to fail

[Mike Kravetz <mike.kravetz@oracle.com>]

On 8/5/19 2:28 AM, Vlastimil Babka wrote:
> On 8/3/19 12:39 AM, Mike Kravetz wrote:
>> When allocating hugetlbfs pool pages via /proc/sys/vm/nr_hugepages,
>> the pages will be interleaved between all nodes of the system.  If
>> nodes are not equal, it is quite possible for one node to fill up
>> before the others.  When this happens, the code still attempts to
>> allocate pages from the full node.  This results in calls to direct
>> reclaim and compaction which slow things down considerably.
>>
>> When allocating pool pages, note the state of the previous allocation
>> for each node.  If previous allocation failed, do not use the
>> aggressive retry algorithm on successive attempts.  The allocation
>> will still succeed if there is memory available, but it will not try
>> as hard to free up memory.
>>
>> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
> 
> Looks like only part of the (agreed with) suggestions were implemented?

My bad, I pulled in the wrong patch.

> - set_max_huge_pages() returns -ENOMEM if nodemask can't be allocated,
> but hugetlb_hstate_alloc_pages() doesn't.

That is somewhat intentional.  The calling context of the two routines is
significantly different.   hugetlb_hstate_alloc_pages is called at boot time
to handle command line parameters.  And, hugetlb_hstate_alloc_pages does not
return a value as it is of type void.

We 'could' print out a warning here.  But, if we can't allocate a node mask
I am pretty sure we will not be able to boot.  I will add a comment.

> - there's still __GFP_NORETRY in nodemask allocations
> - (cosmetics) Mel pointed out that NODEMASK_FREE() works fine with NULL
> pointers

-- 
Mike Kravetz