Re: [PATCH v1 1/4] mm/compaction: enable compacting >0 order folios.

[Zi Yan]

On 13 Nov 2023, at 13:30, Matthew Wilcox wrote:

> On Mon, Nov 13, 2023 at 12:01:54PM -0500, Zi Yan wrote:
>> +	/* this makes migrate_pages() split the source page and retry */
>> +	if (folio_order(src) > 0)
>> +		return NULL;
>
> Nit: folio_test_large() is more efficient than folio_order() > 0.
> The former simply tests the bit, while the second tests the bit, then
> loads folio->_order to check it's >0.  We know it will be, but there's
> no way to tell gcc that if the bit is set, this value is definitely not 0.

Got it. Make sense. Will change it in next version. Thanks.

--
Best Regards,
Yan, Zi

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