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From: Jason Gunthorpe <jgg@nvidia.com>
To: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Wenjia Zhang <wenjia@linux.ibm.com>,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	Gerd Bayer <gbayer@linux.ibm.com>,
	Pierre Morel <pmorel@linux.ibm.com>,
	iommu@lists.linux.dev, linux-s390@vger.kernel.org,
	borntraeger@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com,
	gerald.schaefer@linux.ibm.com, agordeev@linux.ibm.com,
	svens@linux.ibm.com, linux-kernel@vger.kernel.org,
	Julian Ruess <julianr@linux.ibm.com>
Subject: Re: [PATCH v5 5/7] iommu/dma: Allow a single FQ in addition to per-CPU FQs
Date: Mon, 30 Jan 2023 12:40:08 -0400	[thread overview]
Message-ID: <Y9fy6KXdA3OqNudY@nvidia.com> (raw)
In-Reply-To: <8209c172aaa415eace9dcd4b5675ef8506a34538.camel@linux.ibm.com>

On Mon, Jan 30, 2023 at 04:57:56PM +0100, Niklas Schnelle wrote:

> I'm wondering if maybe instead of plain flag bits it makes more sense
> to have a dma_iommu_options struct that contains the queue size and a
> flags value which indicates whether a single or per-CPU queue is
> used.

Querying the driver for what kind of performance tuning it would like
to use by default makes sense to me.

> Then I could add an iommu_ops callback that takes a device and a
> pointer to the dma_iommu_options. That way we can still set the options
> per device but don't need a whole extra domain type. This callback
> would then just be called during initialization of the DMA-FQ domain
> and not having the callback just leaves the defaults unchanged. Does
> that go in the right direction?

I like it

Jason

  reply	other threads:[~2023-01-30 16:40 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-24 12:50 [PATCH v5 0/7] iommu/dma: s390 DMA API conversion and optimized IOTLB flushing Niklas Schnelle
2023-01-24 12:50 ` [PATCH v5 1/7] s390/ism: Set DMA coherent mask Niklas Schnelle
2023-01-24 12:50 ` [PATCH v5 2/7] iommu: Allow .iotlb_sync_map to fail and handle s390's -ENOMEM return Niklas Schnelle
2023-01-24 12:50 ` [PATCH v5 3/7] s390/pci: prepare is_passed_through() for dma-iommu Niklas Schnelle
2023-01-24 12:50 ` [PATCH v5 4/7] s390/pci: Use dma-iommu layer Niklas Schnelle
2023-01-24 12:50 ` [PATCH v5 5/7] iommu/dma: Allow a single FQ in addition to per-CPU FQs Niklas Schnelle
2023-01-30 15:13   ` Robin Murphy
2023-01-30 15:29     ` Jason Gunthorpe
2023-01-30 15:57       ` Niklas Schnelle
2023-01-30 16:40         ` Jason Gunthorpe [this message]
2023-01-30 15:36     ` Niklas Schnelle
2023-01-24 12:50 ` [PATCH v5 6/7] iommu/dma: Enable variable queue size and use larger single queue Niklas Schnelle
2023-01-24 12:50 ` [PATCH v5 7/7] iommu/dma: Add IOMMU op to choose lazy domain type Niklas Schnelle

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