From: Zi Yan <zi.yan@sent.com>
To: David Hildenbrand <david@redhat.com>, linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org,
Michael Ellerman <mpe@ellerman.id.au>,
Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
linuxppc-dev@lists.ozlabs.org,
virtualization@lists.linux-foundation.org,
iommu@lists.linux-foundation.org, Zi Yan <ziy@nvidia.com>
Subject: [RFC PATCH 0/3] Use pageblock_order for cma and alloc_contig_range alignment.
Date: Mon, 15 Nov 2021 14:37:21 -0500 [thread overview]
Message-ID: <20211115193725.737539-1-zi.yan@sent.com> (raw)
From: Zi Yan <ziy@nvidia.com>
Hi David,
You suggested to make alloc_contig_range() deal with pageblock_order instead of
MAX_ORDER - 1 and get rid of MAX_ORDER - 1 dependency in virtio_mem[1]. This
patchset is my attempt to achieve that. Please take a look and let me know if
I am doing it correctly or not.
From what my understanding, cma required alignment of
max(MAX_ORDER - 1, pageblock_order), because when MIGRATE_CMA was introduced,
__free_one_page() does not prevent merging two different pageblocks, when
MAX_ORDER - 1 > pageblock_order. But current __free_one_page() implementation
does prevent that. It should be OK to just align cma to pageblock_order.
alloc_contig_range() relies on MIGRATE_CMA to get free pages, so it can use
pageblock_order as alignment too.
In terms of virtio_mem, if I understand correctly, it relies on
alloc_contig_range() to obtain contiguous free pages and offlines them to reduce
guest memory size. As the result of alloc_contig_range() alignment change,
virtio_mem should be able to just align PFNs to pageblock_order.
Thanks.
[1] https://lore.kernel.org/linux-mm/28b57903-fae6-47ac-7e1b-a1dd41421349@redhat.com/
Zi Yan (3):
mm: cma: alloc_contig_range: use pageblock_order as the single
alignment.
drivers: virtio_mem: use pageblock size as the minimum virtio_mem
size.
arch: powerpc: adjust fadump alignment to be pageblock aligned.
arch/powerpc/include/asm/fadump-internal.h | 4 +---
drivers/virtio/virtio_mem.c | 6 ++----
include/linux/mmzone.h | 5 +----
kernel/dma/contiguous.c | 2 +-
mm/cma.c | 6 ++----
mm/page_alloc.c | 12 +++++-------
6 files changed, 12 insertions(+), 23 deletions(-)
--
2.33.0
next reply other threads:[~2021-11-15 19:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-15 19:37 Zi Yan [this message]
2021-11-15 19:37 ` [RFC PATCH 1/3] mm: cma: alloc_contig_range: use pageblock_order as the single alignment Zi Yan
2021-11-15 19:37 ` [RFC PATCH 2/3] drivers: virtio_mem: use pageblock size as the minimum virtio_mem size Zi Yan
2021-11-15 19:37 ` [RFC PATCH 3/3] arch: powerpc: adjust fadump alignment to be pageblock aligned Zi Yan
2021-11-15 19:37 ` [RFC PATCH 3/3] arch: powerpc: adjust fadump alignment to " Zi Yan
2021-11-16 8:58 ` [RFC PATCH 0/3] Use pageblock_order for cma and alloc_contig_range alignment David Hildenbrand
2021-11-17 3:04 ` Zi Yan
2021-11-23 16:54 ` David Hildenbrand
2021-11-19 12:33 ` Vlastimil Babka
2021-11-19 15:15 ` Zi Yan
2021-11-23 16:35 ` Zi Yan
2021-11-23 17:32 ` Vlastimil Babka
2021-11-29 22:08 ` Zi Yan
2021-11-30 9:11 ` Vlastimil Babka
2021-11-30 10:08 ` Mel Gorman
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