linux-kernel - Re: [PATCH 0/4] drm/msm: Shrinker (and related) fixes

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Date:   Wed, 31 Mar 2021 16:46:10 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Rob Clark <robdclark@...il.com>
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        Rob Clark <robdclark@...omium.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <freedreno@...ts.freedesktop.org>,
        Jordan Crouse <jordan@...micpenguin.net>,
        "Kristian H. Kristensen" <hoegsberg@...gle.com>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/4] drm/msm: Shrinker (and related) fixes

Hi,

On Wed, Mar 31, 2021 at 3:14 PM Rob Clark <robdclark@...il.com> wrote:
>
> From: Rob Clark <robdclark@...omium.org>
>
> I've been spending some time looking into how things behave under high
> memory pressure.  The first patch is a random cleanup I noticed along
> the way.  The second improves the situation significantly when we are
> getting shrinker called from many threads in parallel.  And the last
> two are $debugfs/gem fixes I needed so I could monitor the state of GEM
> objects (ie. how many are active/purgable/purged) while triggering high
> memory pressure.
>
> We could probably go a bit further with dropping the mm_lock in the
> shrinker->scan() loop, but this is already a pretty big improvement.
> The next step is probably actually to add support to unpin/evict
> inactive objects.  (We are part way there since we have already de-
> coupled the iova lifetime from the pages lifetime, but there are a
> few sharp corners to work through.)
>
> Rob Clark (4):
>   drm/msm: Remove unused freed llist node
>   drm/msm: Avoid mutex in shrinker_count()
>   drm/msm: Fix debugfs deadlock
>   drm/msm: Improved debugfs gem stats
>
>  drivers/gpu/drm/msm/msm_debugfs.c      | 14 ++----
>  drivers/gpu/drm/msm/msm_drv.c          |  4 ++
>  drivers/gpu/drm/msm/msm_drv.h          | 10 ++++-
>  drivers/gpu/drm/msm/msm_fb.c           |  3 +-
>  drivers/gpu/drm/msm/msm_gem.c          | 61 +++++++++++++++++++++-----
>  drivers/gpu/drm/msm/msm_gem.h          | 58 +++++++++++++++++++++---
>  drivers/gpu/drm/msm/msm_gem_shrinker.c | 17 +------
>  7 files changed, 122 insertions(+), 45 deletions(-)

This makes a pretty big reduction in jankiness when under memory
pressure and seems to work well for me.

Tested-by: Douglas Anderson <dianders@...omium.org>