linux-kernel - [PATCH] drm/msm: Add debugfs to trigger shrinker

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Message-Id: <20210614150618.729610-1-robdclark@gmail.com>
Date:   Mon, 14 Jun 2021 08:06:18 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Rob Clark <robdclark@...omium.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        linux-arm-msm@...r.kernel.org (open list:DRM DRIVER FOR MSM ADRENO GPU),
        freedreno@...ts.freedesktop.org (open list:DRM DRIVER FOR MSM ADRENO
        GPU), linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] drm/msm: Add debugfs to trigger shrinker

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

Just for the purposes of testing.  Write to it the # of objects to scan,
read back the # freed.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/msm_debugfs.c      | 28 ++++++++++++++++++++++++++
 drivers/gpu/drm/msm/msm_drv.h          |  4 ++++
 drivers/gpu/drm/msm/msm_gem_shrinker.c | 18 +++++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_debugfs.c b/drivers/gpu/drm/msm/msm_debugfs.c
index d611cc8e54a4..7a2b53d35e6b 100644
--- a/drivers/gpu/drm/msm/msm_debugfs.c
+++ b/drivers/gpu/drm/msm/msm_debugfs.c
@@ -108,6 +108,31 @@ static const struct file_operations msm_gpu_fops = {
 	.release = msm_gpu_release,
 };
 
+static unsigned long last_shrink_freed;
+
+static int
+shrink_get(void *data, u64 *val)
+{
+	*val = last_shrink_freed;
+
+	return 0;
+}
+
+static int
+shrink_set(void *data, u64 val)
+{
+	struct drm_device *dev = data;
+
+	last_shrink_freed = msm_gem_shrinker_shrink(dev, val);
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(shrink_fops,
+			shrink_get, shrink_set,
+			"0x%08llx\n");
+
+
 static int msm_gem_show(struct drm_device *dev, struct seq_file *m)
 {
 	struct msm_drm_private *priv = dev->dev_private;
@@ -226,6 +251,9 @@ void msm_debugfs_init(struct drm_minor *minor)
 	debugfs_create_file("gpu", S_IRUSR, minor->debugfs_root,
 		dev, &msm_gpu_fops);
 
+	debugfs_create_file("shrink", S_IRWXU, minor->debugfs_root,
+		dev, &shrink_fops);
+
 	if (priv->kms && priv->kms->funcs->debugfs_init)
 		priv->kms->funcs->debugfs_init(priv->kms, minor);
 }
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 3352125ce428..b58c9d1cc5f1 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -296,6 +296,10 @@ bool msm_use_mmu(struct drm_device *dev);
 int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 		struct drm_file *file);
 
+#ifdef CONFIG_DEBUG_FS
+unsigned long msm_gem_shrinker_shrink(struct drm_device *dev, unsigned long nr_to_scan);
+#endif
+
 void msm_gem_shrinker_init(struct drm_device *dev);
 void msm_gem_shrinker_cleanup(struct drm_device *dev);
 
diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c
index 1187ecf9d647..0f1b29ee04a9 100644
--- a/drivers/gpu/drm/msm/msm_gem_shrinker.c
+++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c
@@ -145,6 +145,24 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 	return (freed > 0) ? freed : SHRINK_STOP;
 }
 
+#ifdef CONFIG_DEBUG_FS
+unsigned long
+msm_gem_shrinker_shrink(struct drm_device *dev, unsigned long nr_to_scan)
+{
+	struct msm_drm_private *priv = dev->dev_private;
+	struct shrink_control sc = {
+		.nr_to_scan = nr_to_scan,
+	};
+	int ret;
+
+	fs_reclaim_acquire(GFP_KERNEL);
+	ret = msm_gem_shrinker_scan(&priv->shrinker, &sc);
+	fs_reclaim_release(GFP_KERNEL);
+
+	return ret;
+}
+#endif
+
 /* since we don't know any better, lets bail after a few
  * and if necessary the shrinker will be invoked again.
  * Seems better than unmapping *everything*
-- 
2.31.1