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From: Leon Romanovsky <leon@kernel.org>
To: Mostafa Saleh <smostafa@google.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Easwar Hariharan <eahariha@linux.microsoft.com>,
	linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
	Jason Gunthorpe <jgg@nvidia.com>
Subject: Re: [PATCH v2 2/2] dma: add IOMMU static calls with clear default ops
Date: Mon, 29 Jul 2024 17:07:36 +0300	[thread overview]
Message-ID: <20240729140736.GC5669@unreal> (raw)
In-Reply-To: <ZqeN6MP4o2JNLcUz@google.com>

On Mon, Jul 29, 2024 at 12:41:12PM +0000, Mostafa Saleh wrote:
> Hi Leon,
> 
> On Wed, Jul 17, 2024 at 03:37:11PM +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
> > 
> > Most of the arch DMA ops (which often, but not  always, involve
> > some sort of IOMMU) are using the same DMA operations. These DMA
> > operations are default ones implemented in drivers/iomem/dma-iommu.c.
> > 
> > So let's make sure to call them directly without need to perform function
> > pointers dereference.
> 
> Just out of curiosity, is there any observed improvement from that?
> As from my experience the DMA-IOMMU path is quite dense so it won't
> be senstive to such micro-optimizations.

DMA-IOMMU no, but NVMe driver which uses DMA-API in datapath will
potentially benefit from this change.

I personally used this change to simplify my "DMA split ... " series [1].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/log/?h=dma-split-v2

Thanks

  reply	other threads:[~2024-07-29 14:07 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-07-17 12:37 [PATCH v2 0/2] DMA IOMMU static calls Leon Romanovsky
2024-07-17 12:37 ` [PATCH v2 1/2] dma: call unconditionally to unmap_page and unmap_sg callbacks Leon Romanovsky
2024-07-18  3:49   ` Christoph Hellwig
2024-07-18  6:33     ` Leon Romanovsky
2024-07-17 12:37 ` [PATCH v2 2/2] dma: add IOMMU static calls with clear default ops Leon Romanovsky
2024-07-18  3:48   ` Christoph Hellwig
2024-07-18  7:04     ` Leon Romanovsky
2024-07-18 12:30       ` Christoph Hellwig
2024-07-18 13:26         ` Leon Romanovsky
2024-07-29 12:41   ` Mostafa Saleh
2024-07-29 14:07     ` Leon Romanovsky [this message]
2024-07-29 17:15     ` Christoph Hellwig
2024-07-30  8:16       ` Leon Romanovsky
2024-07-30 15:26         ` Christoph Hellwig

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