Re: [PATCH 05/10] mm/migrate: demote pages during reclaim

[Oscar Salvador]

On Thu, Apr 01, 2021 at 11:32:25AM -0700, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> 
> This is mostly derived from a patch from Yang Shi:
> 
> 	https://lore.kernel.org/linux-mm/1560468577-101178-10-git-send-email-yang.shi@xxxxxxxxxxxxxxxxx/
> 
> Add code to the reclaim path (shrink_page_list()) to "demote" data
> to another NUMA node instead of discarding the data.  This always
> avoids the cost of I/O needed to read the page back in and sometimes
> avoids the writeout cost when the pagee is dirty.
> 
> A second pass through shrink_page_list() will be made if any demotions
> fail.  This essentally falls back to normal reclaim behavior in the
> case that demotions fail.  Previous versions of this patch may have
> simply failed to reclaim pages which were eligible for demotion but
> were unable to be demoted in practice.
> 
> Note: This just adds the start of infratructure for migration. It is
> actually disabled next to the FIXME in migrate_demote_page_ok().
> 
> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Wei Xu <weixugc@xxxxxxxxxx>
> Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Huang Ying <ying.huang@xxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: osalvador <osalvador@xxxxxxx>

Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>

-- 
Oscar Salvador
SUSE L3