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

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Date: Tue, 20 Feb 2024 10:27:50 -0500
From: Zi Yan <ziy@...dia.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 "\"Huang, Ying\"" <ying.huang@...el.com>,
 Ryan Roberts <ryan.roberts@....com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 "\"Matthew Wilcox (Oracle)\"" <willy@...radead.org>,
 "\"Yin, Fengwei\"" <fengwei.yin@...el.com>, Yu Zhao <yuzhao@...gle.com>,
 Vlastimil Babka <vbabka@...e.cz>,
 "\"Kirill A . Shutemov\"" <kirill.shutemov@...ux.intel.com>,
 Johannes Weiner <hannes@...xchg.org>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>,
 Kemeng Shi <shikemeng@...weicloud.com>,
 Mel Gorman <mgorman@...hsingularity.net>,
 Rohan Puri <rohan.puri15@...il.com>, Mcgrof Chamberlain <mcgrof@...nel.org>,
 Adam Manzanares <a.manzanares@...sung.com>,
 "\"Vishal Moola (Oracle)\"" <vishal.moola@...il.com>
Subject: Re: [PATCH v6 2/4] mm/compaction: enable compacting >0 order folios.

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@...dia.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@...dia.com>
>>> Suggested-by: Huang Ying <ying.huang@...el.com>
>>> Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
>>> Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
>>> Tested-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
>>> Tested-by: Yu Zhao <yuzhao@...gle.com>
>>> Cc: Adam Manzanares <a.manzanares@...sung.com>
>>> Cc: David Hildenbrand <david@...hat.com>
>>> Cc: Johannes Weiner <hannes@...xchg.org>
>>> Cc: Kemeng Shi <shikemeng@...weicloud.com>
>>> Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
>>> Cc: Luis Chamberlain <mcgrof@...nel.org>
>>> Cc: Matthew Wilcox (Oracle) <willy@...radead.org>
>>> Cc: Mel Gorman <mgorman@...hsingularity.net>
>>> Cc: Ryan Roberts <ryan.roberts@....com>
>>> Cc: Vishal Moola (Oracle) <vishal.moola@...il.com>
>>> Cc: Vlastimil Babka <vbabka@...e.cz>
>>> Cc: Yin Fengwei <fengwei.yin@...el.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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