Re: [PATCH v4 2/2] drm/xe/bo: add GPU memory trace points

[Tvrtko Ursulin]

On 12/06/2025 06:40, Lucas De Marchi wrote:
On Wed, Jun 11, 2025 at 03:51:24PM -0700, Juston Li wrote:
Add TRACE_GPU_MEM tracepoints for tracking global and per-process GPU
memory usage.

These are required by VSR on Android 12+ for reporting GPU driver memory
allocations.

v3:
- Use now configurable CONFIG_TRACE_GPU_MEM instead of adding a
  per-driver Kconfig (Lucas)

v2:
- Use u64 as preferred by checkpatch (Tvrtko)
- Fix errors in comments/Kconfig description (Tvrtko)
- drop redundant "CONFIG" in Kconfig

Signed-off-by: Juston Li <justo...@chromium.org>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursu...@igalia.com>
---
drivers/gpu/drm/xe/xe_bo.c           | 47 ++++++++++++++++++++++++++++
drivers/gpu/drm/xe/xe_device_types.h | 16 ++++++++++
2 files changed, 63 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 4e39188a021ab..89a3d23e3b800 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -19,6 +19,8 @@

#include <kunit/static_stub.h>

+#include <trace/events/gpu_mem.h>
+
#include "xe_device.h"
#include "xe_dma_buf.h"
#include "xe_drm_client.h"
@@ -418,6 +420,35 @@ static void xe_ttm_tt_account_subtract(struct 
xe_device *xe, struct ttm_tt *tt)
        xe_shrinker_mod_pages(xe->mem.shrinker, -(long)tt->num_pages, 0);
}

+#if IS_ENABLED(CONFIG_TRACE_GPU_MEM)
+static void update_global_total_pages(struct ttm_device *ttm_dev, 
long num_pages)
+{
+    struct xe_device *xe = ttm_to_xe_device(ttm_dev);
+    u64 global_total_pages =
+        atomic64_add_return(num_pages, &xe->global_total_pages);
+
+    trace_gpu_mem_total(0, 0, global_total_pages << PAGE_SHIFT);
+}
+
+static void update_process_mem(struct drm_file *file, ssize_t size)
+{
+    struct xe_file *xef = to_xe_file(file);
+    u64 process_mem = atomic64_add_return(size, &xef->process_mem);
+
+    rcu_read_lock(); /* Locks file->pid! */
+    trace_gpu_mem_total(0, pid_nr(rcu_dereference(file->pid)), 
process_mem);

Isn't the first arg supposed to be the gpu id? Doesn't this become
invalid when I have e.g. LNL + BMG and the trace is enabled?

Good point.

u32 gpu_id does not seem possible to map to anything useful.

Shall we replace it with a string obtained from dev_name(struct device 
*) ? As only Android parses them I think we can get still away with 
changing the tracepoints ABI.


+    rcu_read_unlock();
+}
+#else
+static inline void update_global_total_pages(struct ttm_device 
*ttm_dev, long num_pages)
+{
+}
+
+static inline void update_process_mem(struct drm_file *file, ssize_t 
size)
+{
+}
+#endif
+
static struct ttm_tt *xe_ttm_tt_create(struct ttm_buffer_object *ttm_bo,
                       u32 page_flags)
{
@@ -525,6 +556,7 @@ static int xe_ttm_tt_populate(struct ttm_device 
*ttm_dev, struct ttm_tt *tt,

    xe_tt->purgeable = false;
    xe_ttm_tt_account_add(ttm_to_xe_device(ttm_dev), tt);
+    update_global_total_pages(ttm_dev, tt->num_pages);

    return 0;
}
@@ -541,6 +573,7 @@ static void xe_ttm_tt_unpopulate(struct ttm_device 
*ttm_dev, struct ttm_tt *tt)

    ttm_pool_free(&ttm_dev->pool, tt);
    xe_ttm_tt_account_subtract(xe, tt);
+    update_global_total_pages(ttm_dev, -(long)tt->num_pages);
}

static void xe_ttm_tt_destroy(struct ttm_device *ttm_dev, struct 
ttm_tt *tt)
@@ -1653,6 +1686,15 @@ static void xe_gem_object_free(struct 
drm_gem_object *obj)
    ttm_bo_put(container_of(obj, struct ttm_buffer_object, base));
}

+#if IS_ENABLED(CONFIG_TRACE_GPU_MEM)
+static int xe_gem_object_open(struct drm_gem_object *obj,
+                  struct drm_file *file_priv)
+{
+    update_process_mem(file_priv, obj->size);
+    return 0;
+}
+#endif
+
static void xe_gem_object_close(struct drm_gem_object *obj,
                struct drm_file *file_priv)
{
@@ -1665,6 +1707,8 @@ static void xe_gem_object_close(struct 
drm_gem_object *obj,
        ttm_bo_set_bulk_move(&bo->ttm, NULL);
        xe_bo_unlock(bo);
    }
+
+    update_process_mem(file_priv, -obj->size);
}

static vm_fault_t xe_gem_fault(struct vm_fault *vmf)
@@ -1762,6 +1806,9 @@ static const struct vm_operations_struct 
xe_gem_vm_ops = {

static const struct drm_gem_object_funcs xe_gem_object_funcs = {
    .free = xe_gem_object_free,
+#if IS_ENABLED(CONFIG_TRACE_GPU_MEM)
+    .open = xe_gem_object_open,
+#endif
    .close = xe_gem_object_close,
    .mmap = drm_gem_ttm_mmap,
    .export = xe_gem_prime_export,
diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/ 
xe/xe_device_types.h
index e5d02a47a5287..b797e766ccbc2 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -641,6 +641,14 @@ struct xe_device {
        unsigned int fsb_freq, mem_freq, is_ddr3;
    };
#endif
+
+#if IS_ENABLED(CONFIG_TRACE_GPU_MEM)
+    /**
+     * @global_total_pages: global GPU page usage tracked for gpu_mem
+     * tracepoints
+     */
+    atomic64_t global_total_pages;
+#endif
};

/**
@@ -702,6 +710,14 @@ struct xe_file {

    /** @refcount: ref count of this xe file */
    struct kref refcount;
+
+#if IS_ENABLED(CONFIG_TRACE_GPU_MEM)
+    /**
+     * @process_mem: per-process GPU memory usage tracked for gpu_mem
+     * tracepoints
+     */
+    atomic64_t process_mem;

so... this is not per-process, it's actually "per dev node" open. Does
this map correctly to the intended use and how it's handled in msm?

Per struct drm_file. Yes it is the same, both do it via 
drm_gem_object_funcs->open/close.

Regards,

Tvrtko


Lucas De Marchi

+#endif
};

#endif
--
2.50.0.rc1.591.g9c95f17f64-goog