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From: Michal Hocko <mhocko@kernel.org>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-api@vger.kernel.org,
	Reinette Chatre <reinette.chatre@intel.com>,
	Christopher Lameter <cl@linux.com>,
	Guy Shattah <sguy@mellanox.com>,
	Anshuman Khandual <khandual@linux.vnet.ibm.com>,
	Michal Nazarewicz <mina86@mina86.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	David Nellans <dnellans@nvidia.com>,
	Laura Abbott <labbott@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	Dave Hansen <dave.hansen@intel.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 2/3] mm: add find_alloc_contig_pages() interface
Date: Tue, 24 Apr 2018 07:37:40 -0600	[thread overview]
Message-ID: <20180424133740.GH17484@dhcp22.suse.cz> (raw)
In-Reply-To: <fc28bcb7-8f9a-e841-0fdf-8636523ebc2a@oracle.com>

On Sun 22-04-18 21:22:07, Mike Kravetz wrote:
> On 04/22/2018 05:09 PM, Michal Hocko wrote:
[...
> > Also do we want to check other usual suspects? E.g. PageReserved? And
> > generally migrateable pages if page count > 0. Or do we want to leave
> > everything to the alloc_contig_range?
> 
> I think you proposed something like the above with limited checking at
> some time in the past.  In my testing, allocations were more likely to
> succeed if we did limited testing here and let alloc_contig_range take
> a shot at migration/allocation.  There really are two ways to approach
> this, do as much checking up front or let it be handled by alloc_contig_range.

OK, it would be great to have a comment mentioning that. The discrepancy
will just hit eyes 

[...]
> Unless I am missing something, calls to alloc_contig range need to have
> a size that is a multiple of page block.  This is because isolation needs
> to take place at a page block level.  We can easily 'round up' and release
> excess pages.

I am not sure but can we simply leave a part of the page block behind? I
mean it might have a misleading migrate type but that shouldn't matter
much, no?

Thanks!
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2018-04-24 13:37 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17  2:09 [PATCH 0/3] Interface for higher order contiguous allocations Mike Kravetz
2018-04-17  2:09 ` [PATCH 1/3] mm: change type of free_contig_range(nr_pages) to unsigned long Mike Kravetz
2018-04-17  2:09 ` [PATCH 2/3] mm: add find_alloc_contig_pages() interface Mike Kravetz
2018-04-17 12:10   ` kbuild test robot
2018-04-18  1:39     ` Mike Kravetz
2018-04-17 14:19   ` kbuild test robot
2018-04-21 16:16   ` Vlastimil Babka
2018-05-02 21:13     ` Mike Kravetz
2018-06-06  9:32       ` Michal Hocko
2018-04-23  0:09   ` Michal Hocko
2018-04-23  4:22     ` Mike Kravetz
2018-04-24 13:37       ` Michal Hocko [this message]
2018-04-17  2:09 ` [PATCH 3/3] mm/hugetlb: use find_alloc_contig_pages() to allocate gigantic pages Mike Kravetz

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