Re: [PATCH v7 04/11] readahead: allocate folios with mapping_min_order in readahead

[Hannes Reinecke <hare@suse.de>]

On 6/17/24 18:10, Matthew Wilcox wrote:
> On Mon, Jun 17, 2024 at 04:04:20PM +0000, Pankaj Raghav (Samsung) wrote:
>> On Mon, Jun 17, 2024 at 01:32:42PM +0100, Matthew Wilcox wrote:
>> So the following can still be there from Hannes patch as we have a
>> stable reference:
>>
>>   		ractl->_workingset |= folio_test_workingset(folio);
>> -		ractl->_nr_pages++;
>> +		ractl->_nr_pages += folio_nr_pages(folio);
>> +		i += folio_nr_pages(folio);
>>   	}
> 
> We _can_, but we just allocated it, so we know what size it is already.
> I'm starting to feel that Hannes' patch should be combined with this
> one.

And we could even make it conditional; on recent devices allocating 64k
(or even 2M) worth of zero pages is not a big deal. And if you have 
machines where this is an issue maybe using large folios isn't the best
of ideas to start with.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
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