[PATCH 0/6] Properly detect swiotlb.

Alex Deucher alexdeucher at gmail.com
Mon Aug 31 09:04:47 PDT 2015

On Wed, Aug 26, 2015 at 2:52 PM,  <jglisse at redhat.com> wrote:
> So this is only build tested as i am away from hardware right now.
> Idea is to provide reliable way to check if swiotlb is in use for
> a device or not. It seems swiotlb_nr_tbl() is no longer reliable
> for that.
> Please test.

Even with these patches applied, we are still ending up in the
ttm_dma_populate() path in the amdgpu driver rather than
ttm_pool_populate() even with a hw iommu enabled.  Any idea?

The attached patch gives us a 20% performance boost in some apps, but
obviously has potential issues if a hw iommu is not present.


> Cheers,
> Jérôme Glisse
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> dri-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
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