From: Christoph Hellwig <hch@lst.de>
To: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>, Baoquan He <bhe@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, cl@linux.com,
John.p.donnelly@oracle.com, kexec@lists.infradead.org,
stable@vger.kernel.org, Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH v3 5/5] mm/slub: do not create dma-kmalloc if no managed pages in DMA zone
Date: Thu, 23 Dec 2021 09:52:38 +0100 [thread overview]
Message-ID: <20211223085238.GA7555@lst.de> (raw)
In-Reply-To: <YcMb7+RESj1nEx9l@ip-172-31-30-232.ap-northeast-1.compute.internal>
On Wed, Dec 22, 2021 at 12:37:03PM +0000, Hyeonggon Yoo wrote:
> Oh I misunderstood this. Underlying physical address of vmalloc()-allocated memory
> can be mapped using DMA API, and it needs to be setup as scatterlist because
> the allocated memory is not physically continuous. Right?
Yes.
> BTW, looking at the API I think the scsi case can be converted to use
> dma_alloc_pages(). but driver requires 512 bytes of buffer and the API
> supports allocating by at least page size.
Overallocating is not generally a problem, but if the allocations are for
a slow path it might make more sense to stick to dma_map_* and bounce
buffer if needed.
> It's not a big problem as it allocates a single buffer but in other
> cases maybe not. Can't we use dma pool for non-coherent pages?
No.
next prev parent reply other threads:[~2021-12-23 8:52 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-13 12:27 [PATCH v3 0/5] Avoid requesting page from DMA zone when no managed pages Baoquan He
2021-12-13 12:27 ` [PATCH v3 1/5] docs: kernel-parameters: Update to reflect the current default size of atomic pool Baoquan He
2021-12-13 14:20 ` john.p.donnelly
2021-12-13 12:27 ` [PATCH v3 2/5] dma-pool: allow user to disable " Baoquan He
2021-12-13 14:21 ` john.p.donnelly
2021-12-13 12:27 ` [PATCH v3 3/5] mm_zone: add function to check if managed dma zone exists Baoquan He
2021-12-13 14:22 ` john.p.donnelly
2021-12-16 10:52 ` David Hildenbrand
2021-12-13 12:27 ` [PATCH v3 4/5] dma/pool: create dma atomic pool only if dma zone has managed pages Baoquan He
2021-12-13 14:23 ` john.p.donnelly
2021-12-13 12:27 ` [PATCH v3 5/5] mm/slub: do not create dma-kmalloc if no managed pages in DMA zone Baoquan He
2021-12-13 13:43 ` Hyeonggon Yoo
2021-12-14 5:32 ` Baoquan He
2021-12-14 10:09 ` Vlastimil Babka
2021-12-14 10:28 ` Christoph Lameter
2021-12-15 4:48 ` Hyeonggon Yoo
2021-12-15 7:03 ` Hyeonggon Yoo
2021-12-15 7:27 ` Christoph Hellwig
2021-12-15 10:34 ` Vlastimil Babka
2021-12-15 11:51 ` David Laight
2021-12-15 13:41 ` Baoquan He
2021-12-17 11:38 ` Hyeonggon Yoo
2021-12-20 7:32 ` Baoquan He
2022-01-07 11:56 ` Hyeonggon Yoo
2021-12-15 14:42 ` Baoquan He
2021-12-15 10:08 ` Baoquan He
2021-12-17 11:38 ` Hyeonggon Yoo
2021-12-21 8:56 ` Christoph Hellwig
2021-12-22 12:37 ` Hyeonggon Yoo
2021-12-23 8:52 ` Christoph Hellwig [this message]
2021-12-13 14:24 ` john.p.donnelly
2021-12-14 16:31 ` Christoph Hellwig
2021-12-14 17:07 ` john.p.donnelly
2021-12-15 7:27 ` Christoph Hellwig
2021-12-13 21:05 ` [PATCH v3 0/5] Avoid requesting page from DMA zone when no managed pages Andrew Morton
2021-12-14 0:35 ` Baoquan He
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