linux-kernel - [PATCH 0/8] drm/msm: Swappable GEM objects

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Date:   Mon,  5 Apr 2021 10:45:23 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Jordan Crouse <jordan@...micpenguin.net>,
        Rob Clark <robdclark@...omium.org>,
        freedreno@...ts.freedesktop.org (open list:DRM DRIVER FOR MSM ADRENO
        GPU),
        linux-arm-msm@...r.kernel.org (open list:DRM DRIVER FOR MSM ADRENO GPU),
        linux-kernel@...r.kernel.org (open list),
        Rob Clark <robdclark@...il.com>
Subject: [PATCH 0/8] drm/msm: Swappable GEM objects

From: Rob Clark <robdclark@...omium.org>

One would normally hope not to be under enough memory pressure to need
to swap GEM objects to disk backed swap.  But memory backed zram swap
(as enabled on chromebooks, for example) can actually be quite fast
and useful on devices with less RAM.  On a 4GB device, opening up ~4
memory intensive web pages (in separate windows rather than tabs, to try
and prevent tab discard), I see ~500MB worth of GEM objects, of which
maybe only 10% are active at any time, and with unpin/evict enabled,
only about half resident (which is a number that gets much lower if you
simulate extreme memory pressure).  Assuming a 2:1 compression ratio (I
see a bit higher in practice, but cannot isolate swapped out GEM pages
vs other), that is like having an extra 100+MB of RAM, or more under
higher memory pressure.

Rob Clark (8):
  drm/msm: ratelimit GEM related WARN_ON()s
  drm/msm: Reorganize msm_gem_shrinker_scan()
  drm/msm: Clear msm_obj->sgt in put_pages()
  drm/msm: Split iova purge and close
  drm/msm: Add $debugfs/gem stats on resident objects
  drm/msm: Track potentially evictable objects
  drm/msm: Small msm_gem_purge() fix
  drm/msm: Support evicting GEM objects to swap

 drivers/gpu/drm/msm/msm_drv.c          |   2 +-
 drivers/gpu/drm/msm/msm_drv.h          |  13 ++-
 drivers/gpu/drm/msm/msm_gem.c          | 155 +++++++++++++++++--------
 drivers/gpu/drm/msm/msm_gem.h          |  68 +++++++++--
 drivers/gpu/drm/msm/msm_gem_shrinker.c | 129 ++++++++++++--------
 drivers/gpu/drm/msm/msm_gpu_trace.h    |  13 +++
 6 files changed, 272 insertions(+), 108 deletions(-)

-- 
2.30.2