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From: Zi Yan <ziy@nvidia.com>
To: "Christian König" <christian.koenig@amd.com>
Cc: David Hildenbrand <david@redhat.com>,
	linux-mm@kvack.org, Matthew Wilcox <willy@infradead.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Michal Hocko <mhocko@kernel.org>,
	John Hubbard <jhubbard@nvidia.com>,
	linux-kernel@vger.kernel.org, Dave Young <dyoung@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>, David Airlie <airlied@linux.ie>,
	kexec@lists.infradead.org, linux-doc@vger.kernel.org,
	dri-devel@lists.freedesktop.org
Subject: Re: [RFC PATCH 13/15] mm: convert MAX_ORDER sized static arrays to dynamic ones.
Date: Thu, 05 Aug 2021 15:58:32 -0400	[thread overview]
Message-ID: <0D3441BA-2A11-4BCA-BFD5-CAB8EB915B8F@nvidia.com> (raw)
In-Reply-To: <586dda97-dc64-ade2-6736-a531e225acbc@amd.com>

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On 5 Aug 2021, at 15:16, Christian König wrote:

> Am 05.08.21 um 21:02 schrieb Zi Yan:
>> From: Zi Yan <ziy@nvidia.com>
>>
>> This prepares for the upcoming changes to make MAX_ORDER a boot time
>> parameter instead of compilation time constant. All static arrays with
>> MAX_ORDER size are converted to pointers and their memory is allocated
>> at runtime.
>
> Well in general I strongly suggest to not use the patter kmalloc(sizeof(some struct) * MAX_ORDER,...) instead use kmalloc_array, kcalloc etc..
>
> Then when a array is embedded at the end of a structure you can use a trailing array and the struct_size() macro to determine the allocation size.

Sure. Will fix it.

>
> Additional to that separating the patch into changes for TTM to make the maximum allocation order independent from MAX_ORDER would be rather good to have I think.

Can you elaborate a little bit more on “make the maximum allocation order independent from MAX_ORDER”? From what I understand of ttm_pool_alloc(), it tries to get num_pages pages by allocating as large pages as possible, starting from MAX_ORDER. What is the rationale behind this algorithm? Why not just call alloc_page(order=0) num_pages times? Is it mean to reduce the number of calls to alloc_page? The allocated pages do not need to get as high as MAX_ORDER, is that the case? If yes, I probably can keep ttm pool as static arrays with length of MIN_MAX_ORDER, which I introduce in Patch 14 as the lower bound of boot time parameter MAX_ORDER. Let me know your thoughts.

Thanks.

—
Best Regards,
Yan, Zi

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  reply	other threads:[~2021-08-05 19:58 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05 19:02 [RFC PATCH 00/15] Make MAX_ORDER adjustable as a kernel boot time parameter Zi Yan
2021-08-05 19:02 ` [RFC PATCH 01/15] arch: x86: remove MAX_ORDER exceeding SECTION_SIZE check for 32bit vdso Zi Yan
2021-08-05 19:02 ` [RFC PATCH 02/15] arch: mm: rename FORCE_MAX_ZONEORDER to ARCH_FORCE_MAX_ORDER Zi Yan
2021-08-05 19:02 ` [RFC PATCH 03/15] mm: check pfn validity when buddy allocator can merge pages across mem sections Zi Yan
2021-08-05 19:02 ` [RFC PATCH 04/15] mm: prevent pageblock size being larger than section size Zi Yan
2021-08-05 19:02 ` [RFC PATCH 05/15] mm/memory_hotplug: online pages at " Zi Yan
2021-08-05 19:02 ` [RFC PATCH 06/15] mm: use PAGES_PER_SECTION instead for mem_map_offset/next() Zi Yan
2021-08-05 19:02 ` [RFC PATCH 07/15] mm: hugetlb: use PAGES_PER_SECTION to check mem_map discontiguity Zi Yan
2021-08-05 19:02 ` [RFC PATCH 08/15] fs: proc: use PAGES_PER_SECTION for page offline checking period Zi Yan
2021-08-07 10:32   ` Mike Rapoport
2021-08-09 15:45     ` [RFC PATCH 08/15] " Zi Yan
2021-08-05 19:02 ` [RFC PATCH 09/15] virtio: virtio_mem: use PAGES_PER_SECTION instead of MAX_ORDER_NR_PAGES Zi Yan
2021-08-09  7:35   ` David Hildenbrand
2021-08-05 19:02 ` [RFC PATCH 10/15] virtio: virtio_balloon: " Zi Yan
2021-08-09  7:42   ` David Hildenbrand
2021-08-05 19:02 ` [RFC PATCH 11/15] mm/page_reporting: report pages at section size instead of MAX_ORDER Zi Yan
2021-08-09  7:25   ` David Hildenbrand
2021-08-09 14:12     ` Alexander Duyck
2021-08-09 15:08       ` Zi Yan
2021-08-09 16:51         ` Alexander Duyck
2021-08-09 14:08   ` Alexander Duyck
2021-08-05 19:02 ` [RFC PATCH 12/15] mm: Make MAX_ORDER of buddy allocator configurable via Kconfig SET_MAX_ORDER Zi Yan
2021-08-06 15:16   ` Vlastimil Babka
2021-08-06 15:23     ` Zi Yan
2021-08-05 19:02 ` [RFC PATCH 13/15] mm: convert MAX_ORDER sized static arrays to dynamic ones Zi Yan
2021-08-05 19:16   ` Christian König
2021-08-05 19:58     ` Zi Yan [this message]
2021-08-06  9:37       ` Christian König
2021-08-06 14:00         ` Zi Yan
2021-08-05 19:02 ` [RFC PATCH 14/15] mm: introduce MIN_MAX_ORDER to replace MAX_ORDER as compile time constant Zi Yan
2021-08-08  8:23   ` Mike Rapoport
2021-08-09 15:35     ` Zi Yan
2021-08-05 19:02 ` [RFC PATCH 15/15] mm: make MAX_ORDER a kernel boot time parameter Zi Yan
2021-08-06 15:36 ` [RFC PATCH 00/15] Make MAX_ORDER adjustable as " Vlastimil Babka
2021-08-06 16:16   ` David Hildenbrand
2021-08-06 16:54     ` Vlastimil Babka
2021-08-06 17:08       ` David Hildenbrand
2021-08-06 18:24         ` Zi Yan
2021-08-09  7:20           ` David Hildenbrand
2021-08-08  7:41       ` Mike Rapoport
2021-08-06 16:32 ` Vlastimil Babka
2021-08-06 17:19   ` Zi Yan
2021-08-06 20:27     ` Hugh Dickins
2021-08-06 21:26       ` Zi Yan
2021-08-09  4:04         ` Hugh Dickins
2021-08-07  1:10       ` Matthew Wilcox
2021-08-07 21:23         ` Matthew Wilcox
2021-08-09  4:29         ` Hugh Dickins
2021-08-09 11:22           ` Matthew Wilcox
2021-08-09  7:41 ` David Hildenbrand

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