Re: [RFC PATCH 0/8] TTM shrinker helpers and xe buffer object shrinker

["Somalapuram, Amaranath" <asomalap@amd.com>]

On 3/29/2024 8:26 PM, Thomas Hellström wrote:
> This series implements TTM shrinker / eviction helpers and an xe bo
> shrinker. It builds on two previous series. First
>
> https://www.mail-archive.com/dri-devel@lists.freedesktop.org/msg484425.html
>
> for patch 1-4, which IMO still could be reviewed and pushed as a
> separate series.
>
> Second the previous TTM shrinker series 
On the latest drm-misc good amount of conflicts on both patch series, 
able to re-base first one, Second on has 16 patches.
If you have latest re-base patches, Please share it.

Regards,
S.Amarnath
> https://lore.kernel.org/linux-mm/b7491378-defd-4f1c-31e2-29e4c77e2d67@amd.com/T/
>
> Where the comment about layering
> https://lore.kernel.org/linux-mm/b7491378-defd-4f1c-31e2-29e4c77e2d67@amd.com/T/#ma918844aa8a6efe8768fdcda0c6590d5c93850c9
>
> now addressed, and this version also implements shmem objects for backup
> rather than direct swap-cache insertions, which was used in the previuos
> series. It turns out that with per-page backup / shrinking, shmem objects
> appears to work just as well as direct swap-cache insertions with the
> added benefit that was introduced in the previous TTM shrinker series to
> avoid running out of swap entries isn't really needed.
>
> In any case, patch 1-4 are better described in their separate series.
> (RFC is removed for those).
>
> Patch 5 could in theory be skipped but introduces a possibility to easily
> add or test multiple backup backends, like the direct swap-cache
> insertion or even files into fast dedicated nvme storage for for example.
>
> Patch 6 introduces helpers in the ttm_pool code for page-by-page shrinking
> and recovery. It avoids having to temporarily allocate a huge amount of
> memory to be able to shrink a buffer object. It also introduces the
> possibility to immediately write-back pages if needed, since that tends
> to be a bit delayed when left to kswapd.
>
> Patch 7 introduces a LRU walk helper for eviction and shrinking. It's
> currently xe-only but not xe-specific and can easily be moved to TTM when
> used by more than one driver or when eviction is implemented using it.
>
> Patch 8 introduces a helper callback for shrinking (Also ready to be
> moved to TTM) and an xe-specific shrinker implementation.
>
> Testing:
> ATM I don't think we have good tests to cover the shrinking functionality
> The series has been tested with a hack that continously creates
> TTM_TT buffer objects until system memory and swap space is exhausted,
> and then reads them back and frees them. However, these tests
> seem to be very slow.
> Ideally a similar test on a machine with very fast solid state or
> similar storage should be set up. Ideally also verifying content
> preservation.
>
> Cc: Somalapuram Amaranath <Amaranath.Somalapuram@amd.com>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: <dri-devel@lists.freedesktop.org>
>
> Thomas Hellström (8):
>    drm/ttm: Allow TTM LRU list nodes of different types
>    drm/ttm: Use LRU hitches
>    drm/ttm, drm/amdgpu, drm/xe: Consider hitch moves within bulk sublist
>      moves
>    drm/ttm: Allow continued swapout after -ENOSPC falure
>    drm/ttm: Add a virtual base class for graphics memory backup
>    drm/ttm/pool: Provide a helper to shrink pages.
>    drm/xe, drm/ttm: Provide a generic LRU walker helper
>    drm/xe: Add a shrinker for xe bos
>
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c |   4 +
>   drivers/gpu/drm/ttm/Makefile           |   2 +-
>   drivers/gpu/drm/ttm/ttm_backup_shmem.c | 137 +++++++++
>   drivers/gpu/drm/ttm/ttm_bo.c           |   1 +
>   drivers/gpu/drm/ttm/ttm_device.c       |  33 ++-
>   drivers/gpu/drm/ttm/ttm_pool.c         | 391 ++++++++++++++++++++++++-
>   drivers/gpu/drm/ttm/ttm_resource.c     | 231 ++++++++++++---
>   drivers/gpu/drm/ttm/ttm_tt.c           |  34 +++
>   drivers/gpu/drm/xe/Makefile            |   2 +
>   drivers/gpu/drm/xe/xe_bo.c             | 123 ++++++--
>   drivers/gpu/drm/xe/xe_bo.h             |   3 +
>   drivers/gpu/drm/xe/xe_device.c         |   8 +
>   drivers/gpu/drm/xe/xe_device_types.h   |   2 +
>   drivers/gpu/drm/xe/xe_shrinker.c       | 237 +++++++++++++++
>   drivers/gpu/drm/xe/xe_shrinker.h       |  18 ++
>   drivers/gpu/drm/xe/xe_ttm_helpers.c    | 224 ++++++++++++++
>   drivers/gpu/drm/xe/xe_ttm_helpers.h    |  63 ++++
>   drivers/gpu/drm/xe/xe_vm.c             |   4 +
>   include/drm/ttm/ttm_backup.h           | 136 +++++++++
>   include/drm/ttm/ttm_device.h           |   2 +
>   include/drm/ttm/ttm_pool.h             |   4 +
>   include/drm/ttm/ttm_resource.h         |  96 +++++-
>   include/drm/ttm/ttm_tt.h               |  19 ++
>   23 files changed, 1683 insertions(+), 91 deletions(-)
>   create mode 100644 drivers/gpu/drm/ttm/ttm_backup_shmem.c
>   create mode 100644 drivers/gpu/drm/xe/xe_shrinker.c
>   create mode 100644 drivers/gpu/drm/xe/xe_shrinker.h
>   create mode 100644 drivers/gpu/drm/xe/xe_ttm_helpers.c
>   create mode 100644 drivers/gpu/drm/xe/xe_ttm_helpers.h
>   create mode 100644 include/drm/ttm/ttm_backup.h
>