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

Mon Apr 8 13:05:00 UTC 2024

Hi, Amaranath,

On Tue, 2024-04-02 at 17:25 +0530, Somalapuram, Amaranath wrote:
> 
> 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.

I was a bit unclear here. This series includes a rebased variant of the
first series, and the rest of this series is a rework of the remaining
patches in the second series below.

So this series is self-contained and the links are provided only for
reference and context. This series still seems to apply using git am -3
on drm-tip, and with a minor single conflict on drm-misc-next.
(Typically we send the patches against drm-tip since that's what CI is
using).

The below series has not been rebased but I have a version of this
series with a direct-swap-cache insertion backend lying around
somewhere. I can post it or share it on gitlab if you want.

Thanks,
/Thomas

> 
> 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 at amd.com>
> > Cc: Christian König <christian.koenig at amd.com>
> > Cc: <dri-devel at 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
> > 