[PATCH RFC v4 05/16] drm, cgroup: Add peak GEM buffer allocation stats

[Kenny Ho <Kenny.Ho@xxxxxxx>]

drm.buffer.peak.stats
        A read-only flat-keyed file which exists on all cgroups.  Each
        entry is keyed by the drm device's major:minor.

        Largest (high water mark) GEM buffer allocated in bytes.

Change-Id: I79e56222151a3d33a76a61ba0097fe93ebb3449f
Signed-off-by: Kenny Ho <Kenny.Ho@xxxxxxx>
---
 Documentation/admin-guide/cgroup-v2.rst |  6 ++++++
 include/linux/cgroup_drm.h              |  3 +++
 kernel/cgroup/drm.c                     | 12 ++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 0e29d136e2f9..8588a0ffc69d 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1907,6 +1907,12 @@ DRM Interface Files
 
 	Total GEM buffer allocation in bytes.
 
+  drm.buffer.peak.stats
+	A read-only flat-keyed file which exists on all cgroups.  Each
+	entry is keyed by the drm device's major:minor.
+
+	Largest (high water mark) GEM buffer allocated in bytes.
+
 GEM Buffer Ownership
 ~~~~~~~~~~~~~~~~~~~~
 
diff --git a/include/linux/cgroup_drm.h b/include/linux/cgroup_drm.h
index 1d8a7f2cdb4e..974d390cfa4f 100644
--- a/include/linux/cgroup_drm.h
+++ b/include/linux/cgroup_drm.h
@@ -15,6 +15,7 @@
 
 enum drmcg_res_type {
 	DRMCG_TYPE_BO_TOTAL,
+	DRMCG_TYPE_BO_PEAK,
 	__DRMCG_TYPE_LAST,
 };
 
@@ -24,6 +25,8 @@ enum drmcg_res_type {
 struct drmcg_device_resource {
 	/* for per device stats */
 	s64			bo_stats_total_allocated;
+
+	s64			bo_stats_peak_allocated;
 };
 
 /**
diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
index 87ae9164d8d8..0bf5b95668c4 100644
--- a/kernel/cgroup/drm.c
+++ b/kernel/cgroup/drm.c
@@ -129,6 +129,9 @@ static void drmcg_print_stats(struct drmcg_device_resource *ddr,
 	case DRMCG_TYPE_BO_TOTAL:
 		seq_printf(sf, "%lld\n", ddr->bo_stats_total_allocated);
 		break;
+	case DRMCG_TYPE_BO_PEAK:
+		seq_printf(sf, "%lld\n", ddr->bo_stats_peak_allocated);
+		break;
 	default:
 		seq_puts(sf, "\n");
 		break;
@@ -177,6 +180,12 @@ struct cftype files[] = {
 		.private = DRMCG_CTF_PRIV(DRMCG_TYPE_BO_TOTAL,
 						DRMCG_FTYPE_STATS),
 	},
+	{
+		.name = "buffer.peak.stats",
+		.seq_show = drmcg_seq_show,
+		.private = DRMCG_CTF_PRIV(DRMCG_TYPE_BO_PEAK,
+						DRMCG_FTYPE_STATS),
+	},
 	{ }	/* terminate */
 };
 
@@ -260,6 +269,9 @@ void drmcg_chg_bo_alloc(struct drmcg *drmcg, struct drm_device *dev,
 		ddr = drmcg->dev_resources[devIdx];
 
 		ddr->bo_stats_total_allocated += (s64)size;
+
+		if (ddr->bo_stats_peak_allocated < (s64)size)
+			ddr->bo_stats_peak_allocated = (s64)size;
 	}
 	mutex_unlock(&dev->drmcg_mutex);
 }
-- 
2.22.0