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From: Christoph Hellwig <hch@lst.de>
To: Tomasz Figa <tfiga@chromium.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Ricardo Ribalda <ribalda@chromium.org>,
	Sergey Senozhatsky <senozhatsky@google.com>,
	"open list:IOMMU DRIVERS" <iommu@lists.linux-foundation.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Media Mailing List <linux-media@vger.kernel.org>
Subject: Re: [PATCH 6/7] dma-iommu: implement ->alloc_noncontiguous
Date: Tue, 16 Feb 2021 09:49:47 +0100	[thread overview]
Message-ID: <20210216084947.GA23897@lst.de> (raw)
In-Reply-To: <CAAFQd5BXAWeB2h4RvqsF1q8ip-Rhew80c7y1_og22-x3rS8KOQ@mail.gmail.com>

On Tue, Feb 16, 2021 at 05:14:55PM +0900, Tomasz Figa wrote:
> When working on the videobuf2 integration with Sergey I noticed that
> we always pass 0 as DMA attrs here, which removes the ability for
> drivers to use DMA_ATTR_ALLOC_SINGLE_PAGES.
> 
> It's quite important from a system stability point of view, because by
> default the iommu_dma allocator would prefer big order allocations for
> TLB locality reasons. For many devices, though, it doesn't really
> affect the performance, because of random access patterns, so single
> pages are good enough and reduce the risk of allocation failures or
> latency due to fragmentation.
> 
> Do you think we could add the attrs parameter to the
> dma_alloc_noncontiguous() API?

Yes, we could probably do that.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Tomasz Figa <tfiga@chromium.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Linux Media Mailing List <linux-media@vger.kernel.org>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"open list:IOMMU DRIVERS" <iommu@lists.linux-foundation.org>,
	Ricardo Ribalda <ribalda@chromium.org>,
	Sergey Senozhatsky <senozhatsky@google.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 6/7] dma-iommu: implement ->alloc_noncontiguous
Date: Tue, 16 Feb 2021 09:49:47 +0100	[thread overview]
Message-ID: <20210216084947.GA23897@lst.de> (raw)
In-Reply-To: <CAAFQd5BXAWeB2h4RvqsF1q8ip-Rhew80c7y1_og22-x3rS8KOQ@mail.gmail.com>

On Tue, Feb 16, 2021 at 05:14:55PM +0900, Tomasz Figa wrote:
> When working on the videobuf2 integration with Sergey I noticed that
> we always pass 0 as DMA attrs here, which removes the ability for
> drivers to use DMA_ATTR_ALLOC_SINGLE_PAGES.
> 
> It's quite important from a system stability point of view, because by
> default the iommu_dma allocator would prefer big order allocations for
> TLB locality reasons. For many devices, though, it doesn't really
> affect the performance, because of random access patterns, so single
> pages are good enough and reduce the risk of allocation failures or
> latency due to fragmentation.
> 
> Do you think we could add the attrs parameter to the
> dma_alloc_noncontiguous() API?

Yes, we could probably do that.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply	other threads:[~2021-02-16  8:50 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-02  9:51 add a new dma_alloc_noncontiguous API v2 Christoph Hellwig
2021-02-02  9:51 ` Christoph Hellwig
2021-02-02  9:51 ` [PATCH 1/7] dma-mapping: remove the {alloc,free}_noncoherent methods Christoph Hellwig
2021-02-02  9:51   ` Christoph Hellwig
2021-02-02  9:51 ` [PATCH 2/7] dma-mapping: add a dma_mmap_pages helper Christoph Hellwig
2021-02-02  9:51   ` Christoph Hellwig
2021-02-02  9:51 ` [PATCH 3/7] dma-mapping: refactor dma_{alloc,free}_pages Christoph Hellwig
2021-02-02  9:51   ` Christoph Hellwig
2021-02-02  9:51 ` [PATCH 4/7] dma-mapping: add a dma_alloc_noncontiguous API Christoph Hellwig
2021-02-02  9:51   ` Christoph Hellwig
2021-02-16 18:55   ` Robin Murphy
2021-02-16 18:55     ` Robin Murphy
2021-03-01  8:09     ` Christoph Hellwig
2021-03-01  8:09       ` Christoph Hellwig
2021-02-02  9:51 ` [PATCH 5/7] dma-iommu: refactor iommu_dma_alloc_remap Christoph Hellwig
2021-02-02  9:51   ` Christoph Hellwig
2021-02-02  9:51 ` [PATCH 6/7] dma-iommu: implement ->alloc_noncontiguous Christoph Hellwig
2021-02-02  9:51   ` Christoph Hellwig
2021-02-16  8:14   ` Tomasz Figa
2021-02-16  8:14     ` Tomasz Figa
2021-02-16  8:49     ` Christoph Hellwig [this message]
2021-02-16  8:49       ` Christoph Hellwig
2021-03-01  7:17       ` Sergey Senozhatsky
2021-03-01  7:17         ` Sergey Senozhatsky
2021-03-01  7:21         ` Christoph Hellwig
2021-03-01  7:21           ` Christoph Hellwig
2021-03-01  8:02           ` Sergey Senozhatsky
2021-03-01  8:02             ` Sergey Senozhatsky
2021-03-01  8:11             ` Christoph Hellwig
2021-03-01  8:11               ` Christoph Hellwig
2021-02-02  9:51 ` [PATCH 7/7] media: uvcvideo: Use dma_alloc_noncontiguos API Christoph Hellwig
2021-02-02  9:51   ` Christoph Hellwig
2021-02-04  7:39   ` Hillf Danton
2021-02-07 18:48 ` add a new dma_alloc_noncontiguous API v2 Christoph Hellwig
2021-02-07 18:48   ` Christoph Hellwig
2021-02-08 11:33   ` Tomasz Figa
2021-02-08 11:33     ` Tomasz Figa
2021-02-09  8:22     ` Christoph Hellwig
2021-02-09  8:29       ` Ricardo Ribalda
2021-02-09  8:29         ` Ricardo Ribalda
2021-02-09 14:46         ` Ricardo Ribalda
2021-02-09 14:46           ` Ricardo Ribalda
2021-02-09 17:02           ` Christoph Hellwig
2021-02-11  9:08             ` Ricardo Ribalda
2021-02-11  9:08               ` Ricardo Ribalda
2021-02-11 13:06               ` Christoph Hellwig
2021-02-11 13:06                 ` Christoph Hellwig
2021-02-11 13:20                 ` Ricardo Ribalda
2021-02-11 13:20                   ` Ricardo Ribalda
2021-02-11 13:55                   ` Laurent Pinchart
2021-02-11 13:55                     ` Laurent Pinchart

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