From: Vlastimil Babka <vbabka@suse.cz>
To: Zi Yan <ziy@nvidia.com>, 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
Subject: Re: [RFC PATCH 0/3] Use pageblock_order for cma and alloc_contig_range alignment.
Date: Fri, 19 Nov 2021 13:33:04 +0100 [thread overview]
Message-ID: <3083463d-978b-fbe6-dadf-670d400ed437@suse.cz> (raw)
In-Reply-To: <20211115193725.737539-1-zi.yan@sent.com>
On 11/15/21 20:37, Zi Yan wrote:
> 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.
But it does prevent that only for isolated pageblock, not CMA, and yout
patchset doesn't seem to expand that to CMA? Or am I missing something.
> 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(-)
>
next prev parent reply other threads:[~2021-11-19 12:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-15 19:37 [RFC PATCH 0/3] Use pageblock_order for cma and alloc_contig_range alignment Zi Yan
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3083463d-978b-fbe6-dadf-670d400ed437@suse.cz \
--to=vbabka@suse.cz \
--cc=david@redhat.com \
--cc=hch@lst.de \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=m.szyprowski@samsung.com \
--cc=mpe@ellerman.id.au \
--cc=robin.murphy@arm.com \
--cc=virtualization@lists.linux-foundation.org \
--cc=ziy@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).