Re: [PATCH v6 2/4] mm/compaction: enable compacting >0 order folios.

[Zi Yan <ziy@nvidia.com>]

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On 20 Feb 2024, at 4:11, David Hildenbrand wrote:

> On 20.02.24 10:03, David Hildenbrand wrote:
>> On 16.02.24 18:04, Zi Yan wrote:
>>> From: Zi Yan <ziy@nvidia.com>
>>>
>>> migrate_pages() supports >0 order folio migration and during compaction,
>>> even if compaction_alloc() cannot provide >0 order free pages,
>>> migrate_pages() can split the source page and try to migrate the base
>>> pages from the split.  It can be a baseline and start point for adding
>>> support for compacting >0 order folios.
>>>
>>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>>> Suggested-by: Huang Ying <ying.huang@intel.com>
>>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>>> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
>>> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>>> Tested-by: Yu Zhao <yuzhao@google.com>
>>> Cc: Adam Manzanares <a.manzanares@samsung.com>
>>> Cc: David Hildenbrand <david@redhat.com>
>>> Cc: Johannes Weiner <hannes@cmpxchg.org>
>>> Cc: Kemeng Shi <shikemeng@huaweicloud.com>
>>> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>>> Cc: Luis Chamberlain <mcgrof@kernel.org>
>>> Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
>>> Cc: Mel Gorman <mgorman@techsingularity.net>
>>> Cc: Ryan Roberts <ryan.roberts@arm.com>
>>> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
>>> Cc: Vlastimil Babka <vbabka@suse.cz>
>>> Cc: Yin Fengwei <fengwei.yin@intel.com>
>>> ---
>>>    mm/compaction.c | 66 ++++++++++++++++++++++++++++++++++++++-----------
>>>    1 file changed, 52 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/mm/compaction.c b/mm/compaction.c
>>> index cc801ce099b4..aa6aad805c4d 100644
>>> --- a/mm/compaction.c
>>> +++ b/mm/compaction.c
>>> @@ -816,6 +816,21 @@ static bool too_many_isolated(struct compact_control *cc)
>>>    	return too_many;
>>>    }
>>>   +/*
>>
>>
>> Can't you add these comments to the respective checks? Like
>>
>> static bool skip_isolation_on_order(int order, int target_order)
>> {
>> 	/*
>> 	 * Unless we are performing global compaction (targert_order <
>> 	 * 0), skip any folios that are larger than the target order: we
>> 	 * wouldn't be here if we'd have a free folio with the desired
>> 	 * target_order, so migrating this folio would likely fail
>> 	 * later.
>> 	 */
>> 	if (target_order != -1 && order >= target_order)
>> 		return true;
>
> I just stumbled over "is_via_compact_memory", likely that should be used instead of the "!= -1 check.

Thanks. Let me use it.


--
Best Regards,
Yan, Zi

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