Subject: Re: [Intel-gfx] [PATCH 0/4] Compact userptr object backing store
 allocation
To: Tvrtko Ursulin <tursulin@ursulin.net>, Intel-gfx@lists.freedesktop.org,
        Andrew Morton <akpm@linux-foundation.org>
References: <1478854220-3255-1-git-send-email-tvrtko.ursulin@linux.intel.com>
Cc: linux-kernel@vger.kernel.org
From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Message-ID: <1676c507-37b4-6bfa-8158-2e373db7e7cc@linux.intel.com>
Date: Mon, 14 Nov 2016 11:45:17 +0000
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Hi Andrew,

On 11/11/2016 08:50, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> Userptr backing store with SWIOTBL active is currently allocated in the same
> inefficient manner, with one sg entry per object page, as what the commit
> 871dfbd67d4e ("drm/i915: Allow compaction upto SWIOTLB max segment size") fixed
> for regular GEM objects.
>
> We can fix that by adding new a __sg_alloc_table_from_pages core function which
> allows us to control the maximum desired coalesced segment size.
>
> Other than that the series starts with two simple fixes to
> sg_alloc_table_from_pages which deal with incorrect data type usage and a
> theoretical overflow condition. Fixing the latter enables easy addition of the
> above mentioned __sg_alloc_table_from_pages.
>
> Tvrtko Ursulin (4):
>   lib/scatterlist: Fix offset type in sg_alloc_table_from_pages
>   lib/scatterlist: Avoid potential scatterlist entry overflow
>   lib/scatterlist: Introduce and export __sg_alloc_table_from_pages
>   drm/i915: Use __sg_alloc_table_from_pages for userptr allocations
>
>  drivers/gpu/drm/i915/i915_drv.h                |  9 +++
>  drivers/gpu/drm/i915/i915_gem.c                | 15 +----
>  drivers/gpu/drm/i915/i915_gem_userptr.c        | 28 ++-------
>  drivers/media/v4l2-core/videobuf2-dma-contig.c |  4 +-
>  drivers/rapidio/devices/rio_mport_cdev.c       |  4 +-
>  include/linux/scatterlist.h                    | 11 ++--
>  lib/scatterlist.c                              | 78 ++++++++++++++++++++------
>  7 files changed, 87 insertions(+), 62 deletions(-)

I have three patches to lib/scatterlist.c in this series which has all 
been reviewed and tested.

We would like to merge them via the DRM tree if there are no objections?

Kind regards,

Tvrtko